node/lib/internal/errors.js
James M Snell 69e6c5a212
http2: major update to internals
This update does several significant things:

1. It eliminates the base Nghttp2* classes and folds those
   in to node::http2::Http2Session and node::http2::Http2Stream
2. It makes node::http2::Http2Stream a StreamBase instance and
   sends that out to JS-land to act as the [kHandle] for the
   JavaScript Http2Stream class.
3. It shifts some of the callbacks from C++ off of the JavaScript
   Http2Session class to the Http2Stream class.
4. It refactors the data provider structure for FD and Stream
   based sending to help encapsulate those functions easier
5. It streamlines some of the functions at the C++ layer to
   eliminate now unnecessary redirections
6. It cleans up node_http2.cc for better readability and
   maintainability
7. It refactors some of the debug output
8. Because Http2Stream instances are now StreamBases, they are
   now also trackable using async-hooks
9. The Stream::OnRead algorithm has been simplified with a
   couple bugs fixed.
10. I've eliminated node_http2_core.h and node_http2_core-inl.h
11. Detect invalid handshake a report protocol error to session
12. Refactor out of memory error, improve other errors
13. Add Http2Session.prototype.ping

PR-URL: https://github.com/nodejs/node/pull/17105
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sebastiaan Deckers <sebdeckers83@gmail.com>
2017-11-21 12:47:54 +01:00

554 lines
20 KiB
JavaScript

/* eslint documented-errors: "error" */
/* eslint alphabetize-errors: "error" */
/* eslint prefer-util-format-errors: "error" */
'use strict';
// The whole point behind this internal module is to allow Node.js to no
// longer be forced to treat every error message change as a semver-major
// change. The NodeError classes here all expose a `code` property whose
// value statically and permanently identifies the error. While the error
// message may change, the code should not.
const kCode = Symbol('code');
const kInfo = Symbol('info');
const messages = new Map();
const { kMaxLength } = process.binding('buffer');
const { defineProperty } = Object;
// Lazily loaded
var util = null;
var buffer;
function makeNodeError(Base) {
return class NodeError extends Base {
constructor(key, ...args) {
super(message(key, args));
defineProperty(this, kCode, {
configurable: true,
enumerable: false,
value: key,
writable: true
});
}
get name() {
return `${super.name} [${this[kCode]}]`;
}
set name(value) {
defineProperty(this, 'name', {
configurable: true,
enumerable: true,
value,
writable: true
});
}
get code() {
return this[kCode];
}
set code(value) {
defineProperty(this, 'code', {
configurable: true,
enumerable: true,
value,
writable: true
});
}
};
}
function lazyBuffer() {
if (buffer === undefined)
buffer = require('buffer').Buffer;
return buffer;
}
// A specialized Error that includes an additional info property with
// additional information about the error condition. The code key will
// be extracted from the context object or the ERR_SYSTEM_ERROR default
// will be used.
class SystemError extends makeNodeError(Error) {
constructor(context) {
context = context || {};
let code = 'ERR_SYSTEM_ERROR';
if (messages.has(context.code))
code = context.code;
super(code,
context.code,
context.syscall,
context.path,
context.dest,
context.message);
Object.defineProperty(this, kInfo, {
configurable: false,
enumerable: false,
value: context
});
}
get info() {
return this[kInfo];
}
get errno() {
return this[kInfo].errno;
}
set errno(val) {
this[kInfo].errno = val;
}
get syscall() {
return this[kInfo].syscall;
}
set syscall(val) {
this[kInfo].syscall = val;
}
get path() {
return this[kInfo].path !== undefined ?
this[kInfo].path.toString() : undefined;
}
set path(val) {
this[kInfo].path = val ?
lazyBuffer().from(val.toString()) : undefined;
}
get dest() {
return this[kInfo].path !== undefined ?
this[kInfo].dest.toString() : undefined;
}
set dest(val) {
this[kInfo].dest = val ?
lazyBuffer().from(val.toString()) : undefined;
}
}
class AssertionError extends Error {
constructor(options) {
if (typeof options !== 'object' || options === null) {
throw new exports.TypeError('ERR_INVALID_ARG_TYPE', 'options', 'Object');
}
var { actual, expected, message, operator, stackStartFunction } = options;
if (message) {
super(message);
} else {
if (actual && actual.stack && actual instanceof Error)
actual = `${actual.name}: ${actual.message}`;
if (expected && expected.stack && expected instanceof Error)
expected = `${expected.name}: ${expected.message}`;
if (util === null) util = require('util');
super(`${util.inspect(actual).slice(0, 128)} ` +
`${operator} ${util.inspect(expected).slice(0, 128)}`);
}
this.generatedMessage = !message;
this.name = 'AssertionError [ERR_ASSERTION]';
this.code = 'ERR_ASSERTION';
this.actual = actual;
this.expected = expected;
this.operator = operator;
Error.captureStackTrace(this, stackStartFunction);
}
}
// This is defined here instead of using the assert module to avoid a
// circular dependency. The effect is largely the same.
function internalAssert(condition, message) {
if (!condition) {
throw new AssertionError({
message,
actual: false,
expected: true,
operator: '=='
});
}
}
function message(key, args) {
const msg = messages.get(key);
internalAssert(msg, `An invalid error message key was used: ${key}.`);
let fmt;
if (typeof msg === 'function') {
fmt = msg;
} else {
if (util === null) util = require('util');
fmt = util.format;
if (args === undefined || args.length === 0)
return msg;
args.unshift(msg);
}
return String(fmt.apply(null, args));
}
// Utility function for registering the error codes. Only used here. Exported
// *only* to allow for testing.
function E(sym, val) {
messages.set(sym, typeof val === 'function' ? val : String(val));
}
module.exports = exports = {
message,
Error: makeNodeError(Error),
TypeError: makeNodeError(TypeError),
RangeError: makeNodeError(RangeError),
URIError: makeNodeError(URIError),
AssertionError,
SystemError,
E // This is exported only to facilitate testing.
};
// To declare an error message, use the E(sym, val) function above. The sym
// must be an upper case string. The val can be either a function or a string.
// The return value of the function must be a string.
// Examples:
// E('EXAMPLE_KEY1', 'This is the error value');
// E('EXAMPLE_KEY2', (a, b) => return `${a} ${b}`);
//
// Once an error code has been assigned, the code itself MUST NOT change and
// any given error code must never be reused to identify a different error.
//
// Any error code added here should also be added to the documentation
//
// Note: Please try to keep these in alphabetical order
//
// Note: Node.js specific errors must begin with the prefix ERR_
E('ERR_ARG_NOT_ITERABLE', '%s must be iterable');
E('ERR_ASSERTION', '%s');
E('ERR_ASYNC_CALLBACK', '%s must be a function');
E('ERR_ASYNC_TYPE', 'Invalid name for async "type": %s');
E('ERR_BUFFER_OUT_OF_BOUNDS', bufferOutOfBounds);
E('ERR_BUFFER_TOO_LARGE',
`Cannot create a Buffer larger than 0x${kMaxLength.toString(16)} bytes`);
E('ERR_CANNOT_WATCH_SIGINT', 'Cannot watch for SIGINT signals');
E('ERR_CHILD_CLOSED_BEFORE_REPLY', 'Child closed before reply received');
E('ERR_CONSOLE_WRITABLE_STREAM',
'Console expects a writable stream instance for %s');
E('ERR_CPU_USAGE', 'Unable to obtain cpu usage %s');
E('ERR_CRYPTO_CUSTOM_ENGINE_NOT_SUPPORTED',
'Custom engines not supported by this OpenSSL');
E('ERR_CRYPTO_ECDH_INVALID_FORMAT', 'Invalid ECDH format: %s');
E('ERR_CRYPTO_ENGINE_UNKNOWN', 'Engine "%s" was not found');
E('ERR_CRYPTO_FIPS_FORCED',
'Cannot set FIPS mode, it was forced with --force-fips at startup.');
E('ERR_CRYPTO_FIPS_UNAVAILABLE', 'Cannot set FIPS mode in a non-FIPS build.');
E('ERR_CRYPTO_HASH_DIGEST_NO_UTF16', 'hash.digest() does not support UTF-16');
E('ERR_CRYPTO_HASH_FINALIZED', 'Digest already called');
E('ERR_CRYPTO_HASH_UPDATE_FAILED', 'Hash update failed');
E('ERR_CRYPTO_INVALID_DIGEST', 'Invalid digest: %s');
E('ERR_CRYPTO_INVALID_STATE', 'Invalid state for operation %s');
E('ERR_CRYPTO_SIGN_KEY_REQUIRED', 'No key provided to sign');
E('ERR_CRYPTO_TIMING_SAFE_EQUAL_LENGTH',
'Input buffers must have the same length');
E('ERR_DNS_SET_SERVERS_FAILED', 'c-ares failed to set servers: "%s" [%s]');
E('ERR_ENCODING_INVALID_ENCODED_DATA',
'The encoded data was not valid for encoding %s');
E('ERR_ENCODING_NOT_SUPPORTED', 'The "%s" encoding is not supported');
E('ERR_FALSY_VALUE_REJECTION', 'Promise was rejected with falsy value');
E('ERR_HTTP2_CONNECT_AUTHORITY',
':authority header is required for CONNECT requests');
E('ERR_HTTP2_CONNECT_PATH',
'The :path header is forbidden for CONNECT requests');
E('ERR_HTTP2_CONNECT_SCHEME',
'The :scheme header is forbidden for CONNECT requests');
E('ERR_HTTP2_FRAME_ERROR',
(type, code, id) => {
let msg = `Error sending frame type ${type}`;
if (id !== undefined)
msg += ` for stream ${id}`;
msg += ` with code ${code}`;
return msg;
});
E('ERR_HTTP2_HEADERS_AFTER_RESPOND',
'Cannot specify additional headers after response initiated');
E('ERR_HTTP2_HEADERS_OBJECT', 'Headers must be an object');
E('ERR_HTTP2_HEADERS_SENT', 'Response has already been initiated.');
E('ERR_HTTP2_HEADER_REQUIRED', 'The %s header is required');
E('ERR_HTTP2_HEADER_SINGLE_VALUE',
'Header field "%s" must have only a single value');
E('ERR_HTTP2_INFO_HEADERS_AFTER_RESPOND',
'Cannot send informational headers after the HTTP message has been sent');
E('ERR_HTTP2_INFO_STATUS_NOT_ALLOWED',
'Informational status codes cannot be used');
E('ERR_HTTP2_INVALID_CONNECTION_HEADERS',
'HTTP/1 Connection specific headers are forbidden: "%s"');
E('ERR_HTTP2_INVALID_HEADER_VALUE', 'Invalid value "%s" for header "%s"');
E('ERR_HTTP2_INVALID_INFO_STATUS',
'Invalid informational status code: %s');
E('ERR_HTTP2_INVALID_PACKED_SETTINGS_LENGTH',
'Packed settings length must be a multiple of six');
E('ERR_HTTP2_INVALID_PSEUDOHEADER',
'"%s" is an invalid pseudoheader or is used incorrectly');
E('ERR_HTTP2_INVALID_SESSION', 'The session has been destroyed');
E('ERR_HTTP2_INVALID_SETTING_VALUE',
'Invalid value for setting "%s": %s');
E('ERR_HTTP2_INVALID_STREAM', 'The stream has been destroyed');
E('ERR_HTTP2_MAX_PENDING_SETTINGS_ACK',
'Maximum number of pending settings acknowledgements (%s)');
E('ERR_HTTP2_NO_SOCKET_MANIPULATION',
'HTTP/2 sockets should not be directly manipulated (e.g. read and written)');
E('ERR_HTTP2_OUT_OF_STREAMS',
'No stream ID is available because maximum stream ID has been reached');
E('ERR_HTTP2_PAYLOAD_FORBIDDEN',
'Responses with %s status must not have a payload');
E('ERR_HTTP2_PING_CANCEL', 'HTTP2 ping cancelled');
E('ERR_HTTP2_PING_LENGTH', 'HTTP2 ping payload must be 8 bytes');
E('ERR_HTTP2_PSEUDOHEADER_NOT_ALLOWED', 'Cannot set HTTP/2 pseudo-headers');
E('ERR_HTTP2_PUSH_DISABLED', 'HTTP/2 client has disabled push streams');
E('ERR_HTTP2_SEND_FILE', 'Only regular files can be sent');
E('ERR_HTTP2_SOCKET_BOUND',
'The socket is already bound to an Http2Session');
E('ERR_HTTP2_STATUS_101',
'HTTP status code 101 (Switching Protocols) is forbidden in HTTP/2');
E('ERR_HTTP2_STATUS_INVALID', 'Invalid status code: %s');
E('ERR_HTTP2_STREAM_CLOSED', 'The stream is already closed');
E('ERR_HTTP2_STREAM_ERROR', 'Stream closed with error code %s');
E('ERR_HTTP2_STREAM_SELF_DEPENDENCY', 'A stream cannot depend on itself');
E('ERR_HTTP2_UNSUPPORTED_PROTOCOL', 'protocol "%s" is unsupported.');
E('ERR_HTTP_HEADERS_SENT',
'Cannot %s headers after they are sent to the client');
E('ERR_HTTP_INVALID_CHAR', 'Invalid character in statusMessage.');
E('ERR_HTTP_INVALID_HEADER_VALUE', 'Invalid value "%s" for header "%s"');
E('ERR_HTTP_INVALID_STATUS_CODE', 'Invalid status code: %s');
E('ERR_HTTP_TRAILER_INVALID',
'Trailers are invalid with this transfer encoding');
E('ERR_INDEX_OUT_OF_RANGE', 'Index out of range');
E('ERR_INSPECTOR_ALREADY_CONNECTED', 'The inspector is already connected');
E('ERR_INSPECTOR_CLOSED', 'Session was closed');
E('ERR_INSPECTOR_NOT_AVAILABLE', 'Inspector is not available');
E('ERR_INSPECTOR_NOT_CONNECTED', 'Session is not connected');
E('ERR_INVALID_ARG_TYPE', invalidArgType);
E('ERR_INVALID_ARG_VALUE', (name, value) =>
`The value "${String(value)}" is invalid for argument "${name}"`);
E('ERR_INVALID_ARRAY_LENGTH',
(name, len, actual) => {
internalAssert(typeof actual === 'number', 'actual must be a number');
return `The array "${name}" (length ${actual}) must be of length ${len}.`;
});
E('ERR_INVALID_ASYNC_ID', 'Invalid %s value: %s');
E('ERR_INVALID_BUFFER_SIZE', 'Buffer size must be a multiple of %s');
E('ERR_INVALID_CALLBACK', 'Callback must be a function');
E('ERR_INVALID_CHAR', invalidChar);
E('ERR_INVALID_CURSOR_POS',
'Cannot set cursor row without setting its column');
E('ERR_INVALID_DOMAIN_NAME', 'Unable to determine the domain name');
E('ERR_INVALID_FD', '"fd" must be a positive integer: %s');
E('ERR_INVALID_FD_TYPE', 'Unsupported fd type: %s');
E('ERR_INVALID_FILE_URL_HOST',
'File URL host must be "localhost" or empty on %s');
E('ERR_INVALID_FILE_URL_PATH', 'File URL path %s');
E('ERR_INVALID_HANDLE_TYPE', 'This handle type cannot be sent');
E('ERR_INVALID_HTTP_TOKEN', '%s must be a valid HTTP token ["%s"]');
E('ERR_INVALID_IP_ADDRESS', 'Invalid IP address: %s');
E('ERR_INVALID_OPT_VALUE', (name, value) =>
`The value "${String(value)}" is invalid for option "${name}"`);
E('ERR_INVALID_OPT_VALUE_ENCODING',
'The value "%s" is invalid for option "encoding"');
E('ERR_INVALID_PERFORMANCE_MARK', 'The "%s" performance mark has not been set');
E('ERR_INVALID_PROTOCOL', 'Protocol "%s" not supported. Expected "%s"');
E('ERR_INVALID_REPL_EVAL_CONFIG',
'Cannot specify both "breakEvalOnSigint" and "eval" for REPL');
E('ERR_INVALID_SYNC_FORK_INPUT',
'Asynchronous forks do not support Buffer, Uint8Array or string input: %s');
E('ERR_INVALID_THIS', 'Value of "this" must be of type %s');
E('ERR_INVALID_TUPLE', '%s must be an iterable %s tuple');
E('ERR_INVALID_URI', 'URI malformed');
E('ERR_INVALID_URL', 'Invalid URL: %s');
E('ERR_INVALID_URL_SCHEME',
(expected) => `The URL must be ${oneOf(expected, 'scheme')}`);
E('ERR_IPC_CHANNEL_CLOSED', 'Channel closed');
E('ERR_IPC_DISCONNECTED', 'IPC channel is already disconnected');
E('ERR_IPC_ONE_PIPE', 'Child process can have only one IPC pipe');
E('ERR_IPC_SYNC_FORK', 'IPC cannot be used with synchronous forks');
E('ERR_METHOD_NOT_IMPLEMENTED', 'The %s method is not implemented');
E('ERR_MISSING_ARGS', missingArgs);
E('ERR_MISSING_DYNAMIC_INSTANTIATE_HOOK',
'The ES Module loader may not return a format of \'dynamic\' when no ' +
'dynamicInstantiate function was provided');
E('ERR_MISSING_MODULE', 'Cannot find module %s');
E('ERR_MODULE_RESOLUTION_LEGACY', '%s not found by import in %s.' +
' Legacy behavior in require() would have found it at %s');
E('ERR_MULTIPLE_CALLBACK', 'Callback called multiple times');
E('ERR_NAPI_CONS_FUNCTION', 'Constructor must be a function');
E('ERR_NAPI_CONS_PROTOTYPE_OBJECT', 'Constructor.prototype must be an object');
E('ERR_NO_CRYPTO', 'Node.js is not compiled with OpenSSL crypto support');
E('ERR_NO_ICU', '%s is not supported on Node.js compiled without ICU');
E('ERR_NO_LONGER_SUPPORTED', '%s is no longer supported');
E('ERR_OUTOFMEMORY', 'Out of memory');
E('ERR_OUT_OF_RANGE', 'The "%s" argument is out of range');
E('ERR_PARSE_HISTORY_DATA', 'Could not parse history data in %s');
E('ERR_REQUIRE_ESM', 'Must use import to load ES Module: %s');
E('ERR_SERVER_ALREADY_LISTEN',
'Listen method has been called more than once without closing.');
E('ERR_SOCKET_ALREADY_BOUND', 'Socket is already bound');
E('ERR_SOCKET_BAD_BUFFER_SIZE', 'Buffer size must be a positive integer');
E('ERR_SOCKET_BAD_PORT', 'Port should be > 0 and < 65536. Received %s.');
E('ERR_SOCKET_BAD_TYPE',
'Bad socket type specified. Valid types are: udp4, udp6');
E('ERR_SOCKET_BUFFER_SIZE', 'Could not get or set buffer size: %s');
E('ERR_SOCKET_CANNOT_SEND', 'Unable to send data');
E('ERR_SOCKET_CLOSED', 'Socket is closed');
E('ERR_SOCKET_DGRAM_NOT_RUNNING', 'Not running');
E('ERR_STDERR_CLOSE', 'process.stderr cannot be closed');
E('ERR_STDOUT_CLOSE', 'process.stdout cannot be closed');
E('ERR_STREAM_CANNOT_PIPE', 'Cannot pipe, not readable');
E('ERR_STREAM_NULL_VALUES', 'May not write null values to stream');
E('ERR_STREAM_PUSH_AFTER_EOF', 'stream.push() after EOF');
E('ERR_STREAM_READ_NOT_IMPLEMENTED', '_read() is not implemented');
E('ERR_STREAM_UNSHIFT_AFTER_END_EVENT', 'stream.unshift() after end event');
E('ERR_STREAM_WRAP', 'Stream has StringDecoder set or is in objectMode');
E('ERR_STREAM_WRITE_AFTER_END', 'write after end');
E('ERR_SYSTEM_ERROR', sysError('A system error occurred'));
E('ERR_TLS_CERT_ALTNAME_INVALID',
'Hostname/IP does not match certificate\'s altnames: %s');
E('ERR_TLS_DH_PARAM_SIZE', 'DH parameter size %s is less than 2048');
E('ERR_TLS_HANDSHAKE_TIMEOUT', 'TLS handshake timeout');
E('ERR_TLS_RENEGOTIATION_FAILED', 'Failed to renegotiate');
E('ERR_TLS_REQUIRED_SERVER_NAME',
'"servername" is required parameter for Server.addContext');
E('ERR_TLS_SESSION_ATTACK', 'TSL session renegotiation attack detected');
E('ERR_TRANSFORM_ALREADY_TRANSFORMING',
'Calling transform done when still transforming');
E('ERR_TRANSFORM_WITH_LENGTH_0',
'Calling transform done when writableState.length != 0');
E('ERR_UNESCAPED_CHARACTERS', '%s contains unescaped characters');
E('ERR_UNHANDLED_ERROR',
(err) => {
const msg = 'Unhandled error.';
if (err === undefined) return msg;
return `${msg} (${err})`;
});
E('ERR_UNKNOWN_ENCODING', 'Unknown encoding: %s');
E('ERR_UNKNOWN_FILE_EXTENSION', 'Unknown file extension: %s');
E('ERR_UNKNOWN_MODULE_FORMAT', 'Unknown module format: %s');
E('ERR_UNKNOWN_SIGNAL', 'Unknown signal: %s');
E('ERR_UNKNOWN_STDIN_TYPE', 'Unknown stdin file type');
E('ERR_UNKNOWN_STREAM_TYPE', 'Unknown stream file type');
E('ERR_V8BREAKITERATOR', 'Full ICU data not installed. ' +
'See https://github.com/nodejs/node/wiki/Intl');
E('ERR_VALID_PERFORMANCE_ENTRY_TYPE',
'At least one valid performance entry type is required');
E('ERR_VALUE_OUT_OF_RANGE', (start, end, value) => {
return `The value of "${start}" must be ${end}. Received "${value}"`;
});
E('ERR_ZLIB_BINDING_CLOSED', 'zlib binding closed');
E('ERR_ZLIB_INITIALIZATION_FAILED', 'Initialization failed');
function sysError(defaultMessage) {
return function(code,
syscall,
path,
dest,
message = defaultMessage) {
if (code !== undefined)
message += `: ${code}`;
if (syscall !== undefined) {
if (code === undefined)
message += ':';
message += ` [${syscall}]`;
}
if (path !== undefined) {
message += `: ${path}`;
if (dest !== undefined)
message += ` => ${dest}`;
}
return message;
};
}
function invalidArgType(name, expected, actual) {
internalAssert(name, 'name is required');
// determiner: 'must be' or 'must not be'
let determiner;
if (typeof expected === 'string' && expected.startsWith('not ')) {
determiner = 'must not be';
expected = expected.replace(/^not /, '');
} else {
determiner = 'must be';
}
let msg;
if (Array.isArray(name)) {
var names = name.map((val) => `"${val}"`).join(', ');
msg = `The ${names} arguments ${determiner} ${oneOf(expected, 'type')}`;
} else if (name.endsWith(' argument')) {
// for the case like 'first argument'
msg = `The ${name} ${determiner} ${oneOf(expected, 'type')}`;
} else {
const type = name.includes('.') ? 'property' : 'argument';
msg = `The "${name}" ${type} ${determiner} ${oneOf(expected, 'type')}`;
}
// if actual value received, output it
if (arguments.length >= 3) {
msg += `. Received type ${actual !== null ? typeof actual : 'null'}`;
}
return msg;
}
function missingArgs(...args) {
internalAssert(args.length > 0, 'At least one arg needs to be specified');
let msg = 'The ';
const len = args.length;
args = args.map((a) => `"${a}"`);
switch (len) {
case 1:
msg += `${args[0]} argument`;
break;
case 2:
msg += `${args[0]} and ${args[1]} arguments`;
break;
default:
msg += args.slice(0, len - 1).join(', ');
msg += `, and ${args[len - 1]} arguments`;
break;
}
return `${msg} must be specified`;
}
function oneOf(expected, thing) {
internalAssert(expected, 'expected is required');
internalAssert(typeof thing === 'string', 'thing is required');
if (Array.isArray(expected)) {
const len = expected.length;
internalAssert(len > 0,
'At least one expected value needs to be specified');
expected = expected.map((i) => String(i));
if (len > 2) {
return `one of ${thing} ${expected.slice(0, len - 1).join(', ')}, or ` +
expected[len - 1];
} else if (len === 2) {
return `one of ${thing} ${expected[0]} or ${expected[1]}`;
} else {
return `of ${thing} ${expected[0]}`;
}
} else {
return `of ${thing} ${String(expected)}`;
}
}
function bufferOutOfBounds(name, isWriting) {
if (isWriting) {
return 'Attempt to write outside buffer bounds';
} else {
return `"${name}" is outside of buffer bounds`;
}
}
function invalidChar(name, field) {
let msg = `Invalid character in ${name}`;
if (field) {
msg += ` ["${field}"]`;
}
return msg;
}