Serialize references to errors in the error priority queue

It doesn't make sense to emit references to future values at higher pri
than the value that they're referencing.

This ensures that we don't emit hard forward references to values that
don't yet exist.

packages/react-client/src/ReactFlightClient.js

@@ -312,6 +312,11 @@ export function parseModelString(
       } else {
         const id = parseInt(value.substring(1), 16);
         const chunk = getChunk(response, id);
+        if (chunk._status === PENDING) {
+          throw new Error(
+            "We didn't expect to see a forward reference. This is a bug in the React Server.",
+          );
+        }
         return readChunk(chunk);
       }
     }

packages/react-server/src/ReactFlightServer.js

@@ -902,7 +902,7 @@ function abortTask(task: Task, request: Request, errorId: number): void {
   // has a single value referencing the error.
   const ref = serializeByValueID(errorId);
   const processedChunk = processReferenceChunk(request, task.id, ref);
-  request.completedJSONChunks.push(processedChunk);
+  request.completedErrorChunks.push(processedChunk);
 }
 
 function flushCompletedChunks(

scripts/error-codes/codes.json

@@ -423,5 +423,6 @@
   "435": "Unexpected Suspense handler tag (%s). This is a bug in React.",
   "436": "Stylesheet resources need a unique representation in the DOM while hydrating and more than one matching DOM Node was found. To fix, ensure you are only rendering one stylesheet link with an href attribute of \"%s\".",
   "437": "the \"precedence\" prop for links to stylesheets expects to receive a string but received something of type \"%s\" instead.",
-  "438": "An unsupported type was passed to use(): %s"
+  "438": "An unsupported type was passed to use(): %s",
+  "439": "We didn't expect to see a forward reference. This is a bug in the React Server."
 }