Clean up symbolicateStackTrace

Summary:
This diff cleans up a bunch of code in `symbolicateStackTrace`. According to motiz88 all of it is dead code and I can confirm symbolication does not break with the changes applied.

Changelog: [Internal]

Reviewed By: yungsters

Differential Revision: D24585849

fbshipit-source-id: 5b2c76f56dbbbf27449ce1472cdd0271ed230c35

Libraries/Core/Devtools/symbolicateStackTrace.js

@@ -12,83 +12,36 @@
 
 const getDevServer = require('./getDevServer');
 
-import NativeSourceCode from '../../NativeModules/specs/NativeSourceCode';
-
-// Avoid requiring fetch on load of this module; see symbolicateStackTrace
-let fetch;
-
 import type {StackFrame} from '../NativeExceptionsManager';
 
-export type CodeFrame = $ReadOnly<{|
+export type CodeFrame = $ReadOnly<{
   content: string,
   location: ?{
     row: number,
     column: number,
     ...
   },
   fileName: string,
-|}>;
+}>;
 
-export type SymbolicatedStackTrace = $ReadOnly<{|
+export type SymbolicatedStackTrace = $ReadOnly<{
   stack: Array<StackFrame>,
   codeFrame: ?CodeFrame,
-|}>;
-
-function isSourcedFromDisk(sourcePath: string): boolean {
-  return !/^http/.test(sourcePath) && /[\\/]/.test(sourcePath);
-}
+}>;
 
 async function symbolicateStackTrace(
   stack: Array<StackFrame>,
 ): Promise<SymbolicatedStackTrace> {
-  // RN currently lazy loads whatwg-fetch using a custom fetch module, which,
-  // when called for the first time, requires and re-exports 'whatwg-fetch'.
-  // However, when a dependency of the project tries to require whatwg-fetch
-  // either directly or indirectly, whatwg-fetch is required before
-  // RN can lazy load whatwg-fetch. As whatwg-fetch checks
-  // for a fetch polyfill before loading, it will in turn try to load
-  // RN's fetch module, which immediately tries to import whatwg-fetch AGAIN.
-  // This causes a circular require which results in RN's fetch module
-  // exporting fetch as 'undefined'.
-  // The fix below postpones trying to load fetch until the first call to symbolicateStackTrace.
-  // At that time, we will have either global.fetch (whatwg-fetch) or RN's fetch.
-  if (!fetch) {
-    // flowlint-next-line untyped-import:off
-    fetch = global.fetch || require('../../Network/fetch').fetch;
-  }
-
   const devServer = getDevServer();
   if (!devServer.bundleLoadedFromServer) {
-    throw new Error('Bundle was not loaded from the packager');
-  }
-
-  let stackCopy = stack;
-
-  const {scriptURL} = NativeSourceCode.getConstants();
-  if (scriptURL) {
-    let foundInternalSource: boolean = false;
-    stackCopy = stack.map((frame: StackFrame) => {
-      if (frame.file == null) {
-        return frame;
-      }
-
-      // If the sources exist on disk rather than appearing to come from the packager,
-      // replace the location with the packager URL until we reach an internal source
-      // which does not have a path (no slashes), indicating a switch from within
-      // the application to a surrounding debugging environment.
-      if (!foundInternalSource && isSourcedFromDisk(frame.file)) {
-        // Copy frame into new object and replace 'file' property
-        return {...frame, file: scriptURL};
-      }
-
-      foundInternalSource = true;
-      return frame;
-    });
+    throw new Error('Bundle was not loaded from Metro.');
   }
 
+  // Lazy-load `fetch` until the first symbolication call to avoid circular requires.
+  const fetch = global.fetch ?? require('../../Network/fetch');
   const response = await fetch(devServer.url + 'symbolicate', {
     method: 'POST',
-    body: JSON.stringify({stack: stackCopy}),
+    body: JSON.stringify({stack}),
   });
   return await response.json();
 }

Libraries/Network/fetch.js

@@ -4,6 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
+ * @flow strict
  * @format
  */