fix: cancellation should not cause incremental completion error (#4259)

incremental completion errors are indicated if and only if null bubbling
has caused a previously sent response to be null

we must instead just give a partial response with errors within the
incremental array

The GraphQL Tools implementation of this feature has different behavior
where the next call will throw if the operation is aborted, but we have
opted to give partial responses, and so we must adjust.

Author: yaacovCR

src/execution/__tests__/abort-signal-test.ts

@@ -100,8 +100,8 @@ describe('Execute: Cancellation', () => {
       errors: [
         {
           message: 'Aborted',
-          path: ['todo', 'id'],
-          locations: [{ line: 4, column: 11 }],
+          path: ['todo'],
+          locations: [{ line: 3, column: 9 }],
         },
       ],
     });
@@ -149,8 +149,8 @@ describe('Execute: Cancellation', () => {
       errors: [
         {
           message: 'Aborted',
-          path: ['todo', 'author', 'id'],
-          locations: [{ line: 6, column: 13 }],
+          path: ['todo', 'author'],
+          locations: [{ line: 5, column: 11 }],
         },
       ],
     });
@@ -198,8 +198,8 @@ describe('Execute: Cancellation', () => {
       errors: [
         {
           message: 'Aborted',
-          path: ['todo', 'id'],
-          locations: [{ line: 4, column: 11 }],
+          path: ['todo'],
+          locations: [{ line: 3, column: 9 }],
         },
       ],
     });
@@ -257,23 +257,28 @@ describe('Execute: Cancellation', () => {
         hasNext: true,
       },
       {
-        completed: [
+        incremental: [
           {
+            data: {
+              text: 'hello world',
+              author: null,
+            },
             errors: [
               {
                 locations: [
                   {
                     column: 13,
-                    line: 6,
+                    line: 7,
                   },
                 ],
                 message: 'Aborted',
-                path: ['todo', 'text'],
+                path: ['todo', 'author'],
               },
             ],
             id: '0',
           },
         ],
+        completed: [{ id: '0' }],
         hasNext: false,
       },
     ]);

src/execution/execute.ts

@@ -729,15 +729,6 @@ function executeFields(
   try {
     for (const [responseName, fieldDetailsList] of groupedFieldSet) {
       const fieldPath = addPath(path, responseName, parentType.name);
-      const abortSignal = exeContext.validatedExecutionArgs.abortSignal;
-      if (abortSignal?.aborted) {
-        throw locatedError(
-          new Error(abortSignal.reason),
-          toNodes(fieldDetailsList),
-          pathToArray(fieldPath),
-        );
-      }
-
       const result = executeField(
         exeContext,
         parentType,
@@ -1737,13 +1728,23 @@ function completeObjectValue(
   incrementalContext: IncrementalContext | undefined,
   deferMap: ReadonlyMap<DeferUsage, DeferredFragmentRecord> | undefined,
 ): PromiseOrValue<GraphQLWrappedResult<ObjMap<unknown>>> {
+  const validatedExecutionArgs = exeContext.validatedExecutionArgs;
+  const abortSignal = validatedExecutionArgs.abortSignal;
+  if (abortSignal?.aborted) {
+    throw locatedError(
+      new Error(abortSignal.reason),
+      toNodes(fieldDetailsList),
+      pathToArray(path),
+    );
+  }
+
   // If there is an isTypeOf predicate function, call it with the
   // current result. If isTypeOf returns false, then raise an error rather
   // than continuing execution.
   if (returnType.isTypeOf) {
     const isTypeOf = returnType.isTypeOf(
       result,
-      exeContext.validatedExecutionArgs.contextValue,
+      validatedExecutionArgs.contextValue,
       info,
     );