RN: Fix Symbolicate Logspew for `/debuggerWorker.js`

Summary:
When remote debugging is enabled, stack traces start at `/debuggerWorker.js`. Since this is not a valid bundle URL, the packager fails to decipher it to find its sourcemap.

This changes the packager to skip the `/debuggerWorker.js` stack frame if one exists.

Reviewed By: frantic

Differential Revision: D3418341

fbshipit-source-id: 7434aa45dea7d120d9d77c060101dd9403989d0c

packager/react-packager/src/Server/__tests__/Server-test.js

@@ -137,7 +137,7 @@ describe('processRequest', () => {
       requestHandler,
       'index.ios.includeRequire.bundle'
     ).then(response => {
-      expect(response.body).toEqual('this is the source')
+      expect(response.body).toEqual('this is the source');
       expect(Bundler.prototype.bundle).toBeCalledWith({
         entryFile: 'index.ios.js',
         inlineSourceMap: false,
@@ -429,6 +429,28 @@ describe('processRequest', () => {
         });
       });
     });
+
+    pit('ignores `/debuggerWorker.js` stack frames', () => {
+      const body = JSON.stringify({stack: [{
+        file: 'http://localhost:8081/debuggerWorker.js',
+        lineNumber: 123,
+        column: 456,
+      }]});
+
+      return makeRequest(
+        requestHandler,
+        '/symbolicate',
+        { rawBody: body }
+      ).then(response => {
+        expect(JSON.parse(response.body)).toEqual({
+          stack: [{
+            file: 'http://localhost:8081/debuggerWorker.js',
+            lineNumber: 123,
+            column: 456,
+          }]
+        });
+      });
+    });
   });
 
   describe('/symbolicate handles errors', () => {

packager/react-packager/src/Server/index.js

@@ -362,7 +362,7 @@ class Server {
         e => {
           res.writeHead(500);
           res.end('Internal Error');
-          console.log(e.stack);
+          console.log(e.stack); // eslint-disable-line no-console-disallow
         }
       );
     } else if (parts[1] === 'graph'){
@@ -491,24 +491,37 @@ class Server {
 
       // In case of multiple bundles / HMR, some stack frames can have
       // different URLs from others
-      const urls = stack.map(frame => frame.file);
-      const uniqueUrls = urls.filter((elem, idx) => urls.indexOf(elem) === idx);
+      const urlIndexes = {};
+      const uniqueUrls = [];
+      stack.forEach(frame => {
+        const sourceUrl = frame.file;
+        // Skip `/debuggerWorker.js` which drives remote debugging because it
+        // does not need to symbolication.
+        if (!urlIndexes.hasOwnProperty(sourceUrl) &&
+            !sourceUrl.endsWith('/debuggerWorker.js')) {
+          urlIndexes[sourceUrl] = uniqueUrls.length;
+          uniqueUrls.push(sourceUrl);
+        }
+      });
 
-      const sourceMaps = uniqueUrls.map(sourceUrl => this._sourceMapForURL(sourceUrl));
+      const sourceMaps = uniqueUrls.map(
+        sourceUrl => this._sourceMapForURL(sourceUrl)
+      );
       return Promise.all(sourceMaps).then(consumers => {
         return stack.map(frame => {
-          const idx = uniqueUrls.indexOf(frame.file);
+          const sourceUrl = frame.file;
+          if (!urlIndexes.hasOwnProperty(sourceUrl)) {
+            return frame;
+          }
+          const idx = urlIndexes[sourceUrl];
           const consumer = consumers[idx];
-
           const original = consumer.originalPositionFor({
             line: frame.lineNumber,
             column: frame.column,
           });
-
           if (!original) {
             return frame;
           }
-
           return Object.assign({}, frame, {
             file: original.source,
             lineNumber: original.line,