Component: Error-Handling

[StachuDotNet]

Darklang raises structured RuntimeErrors upon unexpected/invalid operations in execution.
Each runtime (CLI, Cloud, etc) captures these and decides what to do, with some configurability availed to the user.

This issue is to organize work related to Darklang's error-handling and supporting users' efforts towards preventing, diagnosing, and resolving errors.

• revisit how our existing runtimes handle RTEs
• consider configurability of handling such
• consider allowing users to explicitly raise RTEs

Old specific error reports to consider:

• Got “Unknown error” as a function was throwing an unexpected exception. We hid that exception because we don’t want to show it to grand users, which are not a concern in the CLI
• Got an error “Both values must be the same type” - but which values? That’s not recorded because we assume it’ll be filled in later via traces. But we don’t have traces (maybe we should, but how?)