Add an early invariant to debug a mystery crash (#18159)

packages/react-reconciler/src/ReactFiber.js

@@ -34,6 +34,7 @@ import {
   enableUserTimingAPI,
   enableScopeAPI,
   enableBlocksAPI,
+  throwEarlyForMysteriousError,
 } from 'shared/ReactFeatureFlags';
 import {NoEffect, Placement} from 'shared/ReactSideEffectTags';
 import {ConcurrentRoot, BlockingRoot} from 'shared/ReactRootTags';
@@ -453,6 +454,18 @@ export function createWorkInProgress(current: Fiber, pendingProps: any): Fiber {
     }
   }
 
+  if (throwEarlyForMysteriousError) {
+    // Trying to debug a mysterious internal-only production failure.
+    // See D20130868 and t62461245.
+    // This is only on for RN FB builds.
+    if (current == null) {
+      throw Error('current is ' + current + " but it can't be");
+    }
+    if (workInProgress == null) {
+      throw Error('workInProgress is ' + workInProgress + " but it can't be");
+    }
+  }
+
   workInProgress.childExpirationTime = current.childExpirationTime;
   workInProgress.expirationTime = current.expirationTime;
 

packages/shared/ReactFeatureFlags.js

@@ -105,6 +105,9 @@ export const deferPassiveEffectCleanupDuringUnmount = false;
 // a deprecated pattern we want to get rid of in the future
 export const warnAboutSpreadingKeyToJSX = false;
 
+// Internal-only attempt to debug a React Native issue. See D20130868.
+export const throwEarlyForMysteriousError = false;
+
 // --------------------------
 // Future APIs to be deprecated
 // --------------------------

packages/shared/forks/ReactFeatureFlags.native-fb.js

@@ -50,6 +50,9 @@ export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
 
+// Internal-only attempt to debug a React Native issue. See D20130868.
+export const throwEarlyForMysteriousError = true;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');

packages/shared/forks/ReactFeatureFlags.native-oss.js

@@ -45,6 +45,9 @@ export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
 
+// Internal-only attempt to debug a React Native issue. See D20130868.
+export const throwEarlyForMysteriousError = false;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');

packages/shared/forks/ReactFeatureFlags.persistent.js

@@ -45,6 +45,9 @@ export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
 
+// Internal-only attempt to debug a React Native issue. See D20130868.
+export const throwEarlyForMysteriousError = false;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');

packages/shared/forks/ReactFeatureFlags.test-renderer.js

@@ -45,6 +45,9 @@ export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
 
+// Internal-only attempt to debug a React Native issue. See D20130868.
+export const throwEarlyForMysteriousError = false;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');

packages/shared/forks/ReactFeatureFlags.test-renderer.www.js

@@ -45,6 +45,9 @@ export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
 
+// Internal-only attempt to debug a React Native issue. See D20130868.
+export const throwEarlyForMysteriousError = false;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');

packages/shared/forks/ReactFeatureFlags.testing.js

@@ -45,6 +45,9 @@ export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
 
+// Internal-only attempt to debug a React Native issue. See D20130868.
+export const throwEarlyForMysteriousError = false;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');

packages/shared/forks/ReactFeatureFlags.testing.www.js

@@ -45,6 +45,9 @@ export const runAllPassiveEffectDestroysBeforeCreates = false;
 export const enableModernEventSystem = false;
 export const warnAboutSpreadingKeyToJSX = false;
 
+// Internal-only attempt to debug a React Native issue. See D20130868.
+export const throwEarlyForMysteriousError = false;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');

packages/shared/forks/ReactFeatureFlags.www.js

@@ -99,6 +99,9 @@ export const warnUnstableRenderSubtreeIntoContainer = false;
 
 export const enableModernEventSystem = false;
 
+// Internal-only attempt to debug a React Native issue. See D20130868.
+export const throwEarlyForMysteriousError = false;
+
 // Flow magic to verify the exports of this file match the original version.
 // eslint-disable-next-line no-unused-vars
 type Check<_X, Y: _X, X: Y = _X> = null;