Currently, all error returns from the embedder API specify that an error happened and where. While this is useful, there ought to be a message that makes the error clearer.

An example of the current error reporting: [ERROR:flutter/shell/platform/embedder/embedder.cc(53)] Returning error 'kInvalidArguments' (2) from Flutter Embedder API call to 'FlutterEngineRunInitialized'. Origin: ../../flutter/shell/platform/embedder/embedder.cc:922