Fix (wayfire/backend): Fixed unhandled exception (out_of_range) after no valid outputs in unordered_map

src/modules/wayfire/backend.cpp

@@ -347,10 +347,13 @@ auto IPC::update_state_handler(const std::string& event, const Json::Value& data
 
   if (event == "output-wset-changed") {
     // data: { event, new-wset: wset.name, output: id, new-wset-data: wset, output-data: output }
+    try {
 	  auto& output = state.outputs.at(data["output-data"]["name"].asString());
 	  auto wset_idx = data["new-wset-data"]["index"].asUInt();
 	  state.wsets.at(wset_idx).output = output;
 	  output.wset_idx = wset_idx;
+	} catch (const std::exception&) {
+	} 
     return;
   }