Stack trace on error

[schaefi]

Improve on Error handling

In the beginning errors to the project were always a panic() which leads to interruption at this stage in the code and a stack trace like information. This was not the best solution but it provided exact details about the error and where it happened in the code. With the code changing towards an error reporting up to the main function the information about where in the code something was wrong got lost. In addition the resulting error messages are sometimes unexpressively

Acceptance Criteria

• go over error messages and check of they are expressive
• allow stack trace on error if PILOT_DEBUG is set

[schaefi]

An idea to improve: https://github.com/dtolnay/anyhow

[schaefi]

This affects the pilots in the first place, podman-pilot, firecracker-pilot

[schaefi]

stack trace on error would be nice, but since there is no panic() but error handling up to main it's not so easy to generally create useful trace info