Guard against UIManagerHelper.getUIManager returning null

Summary:
Because the `mCatalystInstance` of the ReactContext can be null during teardown, there are technicaly cases where `UIManagerHelper.getUIManager` can return null. In those cases we check for a CatalystInstance and raise a SoftException, and return null. We must then guard in every case where we call `getUIManager` to prevent NullPointerExceptions.

See T56103679.

Currently crashes are coming from `PropsAnimatedNode.restoreDefaultValues` calling `UIManagerModule.synchronouslyUpdateViewOnUIThread` on teardown/at the end of an animation as RN is being torn down.

This can happen in both Paper and Fabric.

In dev this will still crash because the SoftException will trigger a crash. It will be a noop with logged warnings in production builds.

Changelog: [Internal]

Reviewed By: yungsters

Differential Revision: D18165576

fbshipit-source-id: 7059e04ca339208dd64a0a08a375b565cb8cda02

Author: JoshuaGross

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerHelper.java

@@ -10,22 +10,32 @@
 import static com.facebook.react.uimanager.common.UIManagerType.FABRIC;
 import static com.facebook.react.uimanager.common.ViewUtil.getUIManagerType;
 
+import androidx.annotation.Nullable;
 import com.facebook.react.bridge.CatalystInstance;
 import com.facebook.react.bridge.JSIModuleType;
 import com.facebook.react.bridge.ReactContext;
+import com.facebook.react.bridge.ReactSoftException;
 import com.facebook.react.bridge.UIManager;
 import com.facebook.react.uimanager.common.UIManagerType;
 
 /** Helper class for {@link UIManager}. */
 public class UIManagerHelper {
 
   /** @return a {@link UIManager} that can handle the react tag received by parameter. */
+  @Nullable
   public static UIManager getUIManagerForReactTag(ReactContext context, int reactTag) {
     return getUIManager(context, getUIManagerType(reactTag));
   }
 
   /** @return a {@link UIManager} that can handle the react tag received by parameter. */
+  @Nullable
   public static UIManager getUIManager(ReactContext context, @UIManagerType int uiManagerType) {
+    if (!context.hasActiveCatalystInstance()) {
+      ReactSoftException.logSoftException(
+          "UIManagerHelper",
+          new RuntimeException("Cannot get UIManager: no active Catalyst instance"));
+      return null;
+    }
     CatalystInstance catalystInstance = context.getCatalystInstance();
     return uiManagerType == FABRIC
         ? (UIManager) catalystInstance.getJSIModule(JSIModuleType.UIManager)

ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModule.java

@@ -393,7 +393,9 @@ public void synchronouslyUpdateViewOnUIThread(int tag, ReadableMap props) {
     if (uiManagerType == FABRIC) {
       UIManager fabricUIManager =
           UIManagerHelper.getUIManager(getReactApplicationContext(), uiManagerType);
-      fabricUIManager.synchronouslyUpdateViewOnUIThread(tag, props);
+      if (fabricUIManager != null) {
+        fabricUIManager.synchronouslyUpdateViewOnUIThread(tag, props);
+      }
     } else {
       mUIImplementation.synchronouslyUpdateViewOnUIThread(tag, new ReactStylesDiffMap(props));
     }
@@ -478,7 +480,9 @@ public void updateView(int tag, String className, ReadableMap props) {
     if (uiManagerType == FABRIC) {
       UIManager fabricUIManager =
           UIManagerHelper.getUIManager(getReactApplicationContext(), uiManagerType);
-      fabricUIManager.synchronouslyUpdateViewOnUIThread(tag, props);
+      if (fabricUIManager != null) {
+        fabricUIManager.synchronouslyUpdateViewOnUIThread(tag, props);
+      }
     } else {
       mUIImplementation.updateView(tag, className, props);
     }
@@ -668,14 +672,20 @@ public void dispatchViewManagerCommand(
     // the dispatchViewManagerCommand() method is supported by Fabric JS API.
     if (commandId.getType() == ReadableType.Number) {
       final int commandIdNum = commandId.asInt();
-      UIManagerHelper.getUIManager(
-              getReactApplicationContext(), ViewUtil.getUIManagerType(reactTag))
-          .dispatchCommand(reactTag, commandIdNum, commandArgs);
+      UIManager uiManager =
+          UIManagerHelper.getUIManager(
+              getReactApplicationContext(), ViewUtil.getUIManagerType(reactTag));
+      if (uiManager != null) {
+        uiManager.dispatchCommand(reactTag, commandIdNum, commandArgs);
+      }
     } else if (commandId.getType() == ReadableType.String) {
       final String commandIdStr = commandId.asString();
-      UIManagerHelper.getUIManager(
-              getReactApplicationContext(), ViewUtil.getUIManagerType(reactTag))
-          .dispatchCommand(reactTag, commandIdStr, commandArgs);
+      UIManager uiManager =
+          UIManagerHelper.getUIManager(
+              getReactApplicationContext(), ViewUtil.getUIManagerType(reactTag));
+      if (uiManager != null) {
+        uiManager.dispatchCommand(reactTag, commandIdStr, commandArgs);
+      }
     }
   }
 
@@ -801,7 +811,9 @@ public void sendAccessibilityEvent(int tag, int eventType) {
     if (uiManagerType == FABRIC) {
       UIManager fabricUIManager =
           UIManagerHelper.getUIManager(getReactApplicationContext(), uiManagerType);
-      fabricUIManager.sendAccessibilityEvent(tag, eventType);
+      if (fabricUIManager != null) {
+        fabricUIManager.sendAccessibilityEvent(tag, eventType);
+      }
     } else {
       mUIImplementation.sendAccessibilityEvent(tag, eventType);
     }