Catch exceptions by reference

src/nam_lv2.cpp

@@ -27,7 +27,7 @@ static LV2_Handle instantiate(const LV2_Descriptor*, double rate, const char*, c
 
 		return nullptr;
 	}
-	catch(const std::exception)
+	catch(const std::exception&)
 	{
 		return nullptr;
 	}

src/nam_plugin.cpp

@@ -127,7 +127,7 @@ namespace NAM {
 
 					memcpy(response.path, msg->path, pathlen);
 				}
-				catch (std::exception)
+				catch (const std::exception&)
 				{
 					response.path[0] = '\0';