add comments + test

dev/src/bulk-writer.ts

@@ -190,10 +190,10 @@ class BulkCommitBatch {
     this.state = BatchState.SENT;
 
     // Capture the error stack to preserve stack tracing across async calls.
-    const stack = Error().stack;
+    const stack = Error().stack!;
 
     return this.writeBatch.bulkCommit().catch(err => {
-      throw wrapError(err, stack!);
+      throw wrapError(err, stack);
     });
   }
 

dev/src/index.ts

@@ -910,12 +910,12 @@ export class Firestore {
     const tag = requestTag();
 
     // Capture the error stack to preserve stack tracing across async calls.
-    const stack = Error().stack;
+    const stack = Error().stack!;
 
     return this.initializeIfNeeded(tag).then(() =>
       this.getAll_(documents, fieldMask, tag)
     ).catch(err => {
-      throw wrapError(err, stack!);
+      throw wrapError(err, stack);
     });
   }
 

dev/src/pool.ts

@@ -17,7 +17,7 @@
 import * as assert from 'assert';
 
 import {logger} from './logger';
-import {Deferred, wrapError} from './util';
+import {Deferred} from './util';
 
 /**
  * An auto-resizing pool that distributes concurrent operations over multiple

dev/src/reference.ts

@@ -1809,14 +1809,14 @@ export class Query<T = DocumentData> {
     const docs: Array<QueryDocumentSnapshot<T>> = [];
 
     // Capture the error stack to preserve stack tracing across async calls.
-    const stack = Error().stack;
+    const stack = Error().stack!;
 
     return new Promise((resolve, reject) => {
       let readTime: Timestamp;
 
       this._stream(transactionId)
         .on('error', err => {
-          reject(wrapError(err, stack!));
+          reject(wrapError(err, stack));
         })
         .on('data', result => {
           readTime = result.readTime;

dev/src/util.ts

@@ -154,7 +154,7 @@ export function isPermanentRpcError(
  * @private
  */
 export function wrapError(err: Error, stack: string): Error {
-  let wrappedError = new Error(err.message);
+  const wrappedError = new Error(err.message);
   wrappedError.stack += '\nCaused by: ' + stack;
   wrappedError.stack += '\nCaused by: ' + err.stack;
   return wrappedError;

dev/src/write-batch.ts

@@ -532,12 +532,11 @@ export class WriteBatch {
    * });
    */
   commit(): Promise<WriteResult[]> {
-
     // Capture the error stack to preserve stack tracing across async calls.
-    const stack = Error().stack;
+    const stack = Error().stack!;
 
     return this.commit_().catch(err => {
-      throw wrapError(err, stack!);
+      throw wrapError(err, stack);
     });
   }
 

dev/system-test/firestore.ts

@@ -2148,6 +2148,17 @@ describe('WriteBatch class', () => {
       });
   });
 
+  it('has a full stack trace if set() errors', () => {
+    // Use an invalid document name that the backend will reject.
+    const ref = randomCol.doc('__doc__');
+    const batch = firestore.batch();
+    batch.set(ref, {foo: 'a'});
+    return batch.commit().then(() => Promise.reject('commit() should have failed')
+    ).catch((err: Error) => {
+      expect(err.stack).to.contain('WriteBatch.commit');
+    });
+  });
+
   it('has update() method', () => {
     const ref = randomCol.doc('doc');
     const batch = firestore.batch();