Refactor UIManagerHelper.getUIManager

Summary:
This diff refactors the UIManagerHelper.getUIManager to allow the caller determine if it should return null when catalyst Istance is not active.
This is necessary in order to keep backward compatibility for the getEventDispatcher method.

changelog: [internal]

Reviewed By: makovkastar

Differential Revision: D19383063

fbshipit-source-id: 8a46b61d212480be91ea78929bbfa7248d5f3ad9

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

@@ -34,14 +34,34 @@ public class UIManagerHelper {
   /** @return a {@link UIManager} that can handle the react tag received by parameter. */
   @Nullable
   public static UIManager getUIManager(ReactContext context, @UIManagerType int uiManagerType) {
+    return getUIManager(context, uiManagerType, true);
+  }
+
+  @Nullable
+  private static UIManager getUIManager(
+      ReactContext context,
+      @UIManagerType int uiManagerType,
+      boolean returnNullIfCatalystIsInactive) {
     if (context.isBridgeless()) {
       return (UIManager) context.getJSIModule(JSIModuleType.UIManager);
     } else {
+      if (!context.hasCatalystInstance()) {
+        ReactSoftException.logSoftException(
+            "UIManagerHelper",
+            new IllegalStateException(
+                "Cannot get UIManager because the context doesn't contain a CatalystInstance."));
+        return null;
+      }
+      // TODO T60461551: add tests to verify emission of events when the ReactContext is being turn
+      // down.
       if (!context.hasActiveCatalystInstance()) {
         ReactSoftException.logSoftException(
             "UIManagerHelper",
-            new RuntimeException("Cannot get UIManager: no active Catalyst instance"));
-        return null;
+            new IllegalStateException(
+                "Cannot get UIManager because the context doesn't contain an active CatalystInstance."));
+        if (returnNullIfCatalystIsInactive) {
+          return null;
+        }
       }
       CatalystInstance catalystInstance = context.getCatalystInstance();
       return uiManagerType == FABRIC
@@ -66,7 +86,7 @@ public class UIManagerHelper {
   @Nullable
   public static EventDispatcher getEventDispatcher(
       ReactContext context, @UIManagerType int uiManagerType) {
-    UIManager uiManager = getUIManager(context, uiManagerType);
+    UIManager uiManager = getUIManager(context, uiManagerType, false);
     return uiManager == null ? null : (EventDispatcher) uiManager.getEventDispatcher();
   }