Change performAndReportError to handle exception pointers

Summary: Since plugins aren't under our control, they might throw exception pointers. We can still extract the useful info in this case.

Reviewed By: passy

Differential Revision: D14244362

fbshipit-source-id: 5f18100c08160e7514b3fd88ec47809cb37e9770

xplat/Flipper/FlipperClient.h

@@ -110,6 +110,7 @@ class FlipperClient : public FlipperConnectionManager::Callbacks {
   void disconnect(std::shared_ptr<FlipperPlugin> plugin);
   void startBackgroundPlugins();
   std::string callstack();
+  void handleError(std::exception& e);
 };
 
 } // namespace flipper