[WASM] improve error logging

Summary: Emscripten instead of errors returns to JS pointer to error. To get meaningful message we need to pass this pointer back to C++, read value from it and return error.what() as string.

Test Plan:

1. Add this code auto x = SQLiteQueryExecutor::getStorage().get<Draft>("123"); and check if error from ORM is visible:

2. Add this code throw std::runtime_error("TEST ERROR"); and check if error is visible:

3. Use null pointer
4. User not existing pointer

Reviewers: tomek, michal, marcin

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D10396