Avoid unhandled rejection errors for Promises that we intentionally ignore

In the final passes, we ignore the newly generated Promises and use
the previous ones. This ensures that if those generate errors, that we
intentionally ignore those.

Author: sebmarkbage

packages/react-reconciler/src/ReactFiberHooks.new.js

@@ -768,6 +768,8 @@ if (enableUseMemoCacheHook) {
   };
 }
 
+function noop(): void {}
+
 function use<T>(usable: Usable<T>): T {
   if (usable !== null && typeof usable === 'object') {
     // $FlowFixMe[method-unbinding]
@@ -793,6 +795,11 @@ function use<T>(usable: Usable<T>): T {
             index,
           );
           if (prevThenableAtIndex !== null) {
+            if (thenable !== prevThenableAtIndex) {
+              // Avoid an unhandled rejection errors for the Promises that we'll
+              // intentionally ignore.
+              thenable.then(noop, noop);
+            }
             switch (prevThenableAtIndex.status) {
               case 'fulfilled': {
                 const fulfilledValue: T = prevThenableAtIndex.value;

packages/react-reconciler/src/ReactFiberHooks.old.js

@@ -768,6 +768,8 @@ if (enableUseMemoCacheHook) {
   };
 }
 
+function noop(): void {}
+
 function use<T>(usable: Usable<T>): T {
   if (usable !== null && typeof usable === 'object') {
     // $FlowFixMe[method-unbinding]
@@ -793,6 +795,11 @@ function use<T>(usable: Usable<T>): T {
             index,
           );
           if (prevThenableAtIndex !== null) {
+            if (thenable !== prevThenableAtIndex) {
+              // Avoid an unhandled rejection errors for the Promises that we'll
+              // intentionally ignore.
+              thenable.then(noop, noop);
+            }
             switch (prevThenableAtIndex.status) {
               case 'fulfilled': {
                 const fulfilledValue: T = prevThenableAtIndex.value;

packages/react-server/src/ReactFizzHooks.js

@@ -610,6 +610,11 @@ function use<T>(usable: Usable<T>): T {
             index,
           );
           if (prevThenableAtIndex !== null) {
+            if (thenable !== prevThenableAtIndex) {
+              // Avoid an unhandled rejection errors for the Promises that we'll
+              // intentionally ignore.
+              thenable.then(noop, noop);
+            }
             switch (prevThenableAtIndex.status) {
               case 'fulfilled': {
                 const fulfilledValue: T = prevThenableAtIndex.value;

packages/react-server/src/ReactFlightHooks.js

@@ -121,6 +121,8 @@ function useId(): string {
   return ':' + currentRequest.identifierPrefix + 'S' + id.toString(32) + ':';
 }
 
+function noop(): void {}
+
 function use<T>(usable: Usable<T>): T {
   if (usable !== null && typeof usable === 'object') {
     // $FlowFixMe[method-unbinding]
@@ -147,6 +149,11 @@ function use<T>(usable: Usable<T>): T {
             index,
           );
           if (prevThenableAtIndex !== null) {
+            if (thenable !== prevThenableAtIndex) {
+              // Avoid an unhandled rejection errors for the Promises that we'll
+              // intentionally ignore.
+              thenable.then(noop, noop);
+            }
             switch (prevThenableAtIndex.status) {
               case 'fulfilled': {
                 const fulfilledValue: T = prevThenableAtIndex.value;