bugfix: Only handle first javascript fatal error (facebook#47914)

Summary:
Pull Request resolved: facebook#47914

This was a bug in the original diff: D66193194.

If a fatal js error happens, we should only drop subsequent **fatal** js errors. It's fine to report soft errors.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D66392706

fbshipit-source-id: c51bae186184c54faa9bce065b81b442607e751b

Author: RSNara

packages/react-native/ReactCommon/jserrorhandler/JsErrorHandler.cpp

@@ -379,11 +379,14 @@ void JsErrorHandler::handleErrorWithCppPipeline(
     }
   }
 
-  if (*shouldPreventDefault || _hasHandledFatalError) {
+  if (*shouldPreventDefault) {
     return;
   }
 
   if (isFatal) {
+    if (_hasHandledFatalError) {
+      return;
+    }
     _hasHandledFatalError = true;
   }