Unify behavior for internal server errors

[php-coder]

The generated apps should behave similarly in case of internal server errors. For instance, at the moment, express-based apps don't handle the exception and shutdown a whole application!

Let's return 500 status code in that case with { "error": "Internal Server Error" } body.

• fix Express+JS
  • https://www.robinwieruch.de/node-express-error-handling/
• fix Express+TS
  • https://github.com/DefinitelyTyped/DefinitelyTyped/blob/be9af00ee708c952d35532e8c0099a66acb16675/types/express/express-tests.ts#L35
  • https://github.com/DefinitelyTyped/DefinitelyTyped/blob/aa4519bcb671148fe59259f6b25b7bebbb170a3d/types/express-serve-static-core/index.d.ts#L26-L38
• fix Golang
• fix FastAPI
  • https://fastapi.tiangolo.com/tutorial/handling-errors/#install-custom-exception-handlers