react-native/Libraries/Core/ExceptionsManager.js

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 * @flow strict
 */

'use strict';

import type {ExtendedError} from './ExtendedError';
import type {ExceptionData} from './NativeExceptionsManager';

class SyntheticError extends Error {
  name: string = '';
}

type ExceptionDecorator = ExceptionData => ExceptionData;

let userExceptionDecorator: ?ExceptionDecorator;
let inUserExceptionDecorator = false;

/**
 * Allows the app to add information to the exception report before it is sent
 * to native. This API is not final.
 */

function unstable_setExceptionDecorator(
  exceptionDecorator: ?ExceptionDecorator,
) {
  userExceptionDecorator = exceptionDecorator;
}

function preprocessException(data: ExceptionData): ExceptionData {
  if (userExceptionDecorator && !inUserExceptionDecorator) {
    inUserExceptionDecorator = true;
    try {
      return userExceptionDecorator(data);
    } catch {
      // Fall through
    } finally {
      inUserExceptionDecorator = false;
    }
  }
  return data;
}

/**
 * Handles the developer-visible aspect of errors and exceptions
 */
let exceptionID = 0;
function reportException(
  e: ExtendedError,
  isFatal: boolean,
  reportToConsole: boolean, // only true when coming from handleException; the error has not yet been logged
) {
  const parseErrorStack = require('./Devtools/parseErrorStack');
  const stack = parseErrorStack(e?.stack);
  const currentExceptionID = ++exceptionID;
  const originalMessage = e.message || '';
  let message = originalMessage;
  if (e.componentStack != null) {
    message += `\n\nThis error is located at:${e.componentStack}`;
  }
  const namePrefix = e.name == null || e.name === '' ? '' : `${e.name}: `;

  if (!message.startsWith(namePrefix)) {
    message = namePrefix + message;
  }

  message =
    e.jsEngine == null ? message : `${message}, js engine: ${e.jsEngine}`;

  const data = preprocessException({
    message,
    originalMessage: message === originalMessage ? null : originalMessage,
    name: e.name == null || e.name === '' ? null : e.name,
    componentStack:
      typeof e.componentStack === 'string' ? e.componentStack : null,
    stack,
    id: currentExceptionID,
    isFatal,
    extraData: {
      jsEngine: e.jsEngine,
      rawStack: e.stack,
    },
  });

  if (reportToConsole) {
    // we feed back into console.error, to make sure any methods that are
    // monkey patched on top of console.error are called when coming from
    // handleException
    console.error(data.message);
  }

  if (__DEV__) {
    const LogBox = require('../LogBox/LogBox');
    LogBox.addException({
      ...data,
      isComponentError: !!e.isComponentError,
    });
  } else if (isFatal || e.type !== 'warn') {
    const NativeExceptionsManager =
      require('./NativeExceptionsManager').default;
    if (NativeExceptionsManager) {
      NativeExceptionsManager.reportException(data);
    }
  }
}

declare var console: typeof console & {
  _errorOriginal: typeof console.error,
  reportErrorsAsExceptions: boolean,
  ...
};

// If we trigger console.error _from_ handleException,
// we do want to make sure that console.error doesn't trigger error reporting again
let inExceptionHandler = false;

/**
 * Logs exceptions to the (native) console and displays them
 */
function handleException(e: mixed, isFatal: boolean) {
  let error: Error;
  if (e instanceof Error) {
    error = e;
  } else {
    // Workaround for reporting errors caused by `throw 'some string'`
    // Unfortunately there is no way to figure out the stacktrace in this
    // case, so if you ended up here trying to trace an error, look for
    // `throw '<error message>'` somewhere in your codebase.
    error = new SyntheticError(e);
  }
  try {
    inExceptionHandler = true;
    /* $FlowFixMe[class-object-subtyping] added when improving typing for this
     * parameters */
    reportException(error, isFatal, /*reportToConsole*/ true);
  } finally {
    inExceptionHandler = false;
  }
}

/* $FlowFixMe[missing-local-annot] The type annotation(s) required by Flow's
 * LTI update could not be added via codemod */
function reactConsoleErrorHandler(...args) {
  // bubble up to any original handlers
  console._errorOriginal(...args);
  if (!console.reportErrorsAsExceptions) {
    return;
  }
  if (inExceptionHandler) {
    // The fundamental trick here is that are multiple entry point to logging errors:
    // (see D19743075 for more background)
    //
    // 1. An uncaught exception being caught by the global handler
    // 2. An error being logged throw console.error
    //
    // However, console.error is monkey patched multiple times: by this module, and by the
    // DevTools setup that sends messages to Metro.
    // The patching order cannot be relied upon.
    //
    // So, some scenarios that are handled by this flag:
    //
    // Logging an error:
    // 1. console.error called from user code
    // 2. (possibly) arrives _first_ at DevTool handler, send to Metro
    // 3. Bubbles to here
    // 4. goes into report Exception.
    // 5. should not trigger console.error again, to avoid looping / logging twice
    // 6. should still bubble up to original console
    //    (which might either be console.log, or the DevTools handler in case it patched _earlier_ and (2) didn't happen)
    //
    // Throwing an uncaught exception:
    // 1. exception thrown
    // 2. picked up by handleException
    // 3. should be send to console.error (not console._errorOriginal, as DevTools might have patched _later_ and it needs to send it to Metro)
    // 4. that _might_ bubble again to the `reactConsoleErrorHandle` defined here
    //    -> should not handle exception _again_, to avoid looping / showing twice (this code branch)
    // 5. should still bubble up to original console (which might either be console.log, or the DevTools handler in case that one patched _earlier_)
    return;
  }

  let error;

  const firstArg = args[0];
  if (firstArg?.stack) {
    // reportException will console.error this with high enough fidelity.
    error = firstArg;
  } else {
    const stringifySafe = require('../Utilities/stringifySafe').default;
    if (typeof firstArg === 'string' && firstArg.startsWith('Warning: ')) {
      // React warnings use console.error so that a stack trace is shown, but
      // we don't (currently) want these to show a redbox
      // (Note: Logic duplicated in polyfills/console.js.)
      return;
    }
    const message = args
      .map(arg => (typeof arg === 'string' ? arg : stringifySafe(arg)))
      .join(' ');

    error = new SyntheticError(message);
    error.name = 'console.error';
  }

  reportException(
    /* $FlowFixMe[class-object-subtyping] added when improving typing for this
     * parameters */
    error,
    false, // isFatal
    false, // reportToConsole
  );
}

/**
 * Shows a redbox with stacktrace for all console.error messages.  Disable by
 * setting `console.reportErrorsAsExceptions = false;` in your app.
 */
function installConsoleErrorReporter() {
  // Enable reportErrorsAsExceptions
  if (console._errorOriginal) {
    return; // already installed
  }
  // Flow doesn't like it when you set arbitrary values on a global object
  console._errorOriginal = console.error.bind(console);
  console.error = reactConsoleErrorHandler;
  if (console.reportErrorsAsExceptions === undefined) {
    // Individual apps can disable this
    // Flow doesn't like it when you set arbitrary values on a global object
    console.reportErrorsAsExceptions = true;
  }
}

module.exports = {
  handleException,
  installConsoleErrorReporter,
  SyntheticError,
  unstable_setExceptionDecorator,
};