Tweak to avoid property read (#14593)

Author: aweary

packages/react-reconciler/src/ReactFiberUnwindWork.js

@@ -214,8 +214,9 @@ function throwException(
 // attach another listener to flip the boundary back to its normal state.
 constthenables: Set<Thenable> = (workInProgress.updateQueue: any);
  if (thenables === null) {
-workInProgress.updateQueue=(newSet(): any);
-workInProgress.updateQueue.add(thenable);
+constupdateQueue=(newSet(): any);
+updateQueue.add(thenable);
+workInProgress.updateQueue=updateQueue;
 } else {
 thenables.add(thenable);
 }