refactor error handling and add more tests

[XuyangSong]

• refactor error handling module to ensure proper error msgs produced
• much more tests to cover exception cases
• "Switch to our forked heliaxdev/lambdaworks dependency, as there are crashes in the original lambdaworks library and the lambdaclass team has recently removed the cairo-backend from their release, and they will no longer maintain the cairo-prover. I have fixed these crashes in our heliaxdev/lambdaworks version. We can discuss if this is a viable long-term solution for us.