Return status when failed calls

[Thanatermesis]

Issue

Cecli should return the exit status when fails, for example:

~ ❯❯❯ cecli mycode.c -m "do foo and bar"
────────────────────────────────────────────────────────────────────────────
litellm.MidStreamFallbackError: litellm.ServiceUnavailableError:
Vertex_ai_betaException -
{
  "error": {
    "code": 503,
    "message": "This model is currently experiencing high demand. Spikes in
demand are usually temporary. Please try again later.",
    "status": "UNAVAILABLE"
  }
}
 Original exception: ServiceUnavailableError:
litellm.ServiceUnavailableError: Vertex_ai_betaException -
{
  "error": {
    "code": 503,
    "message": "This model is currently experiencing high demand. Spikes in
demand are usually temporary. Please try again later.",
    "status": "UNAVAILABLE"
  }
}

Response parsing error.
~ ❯❯❯ echo $?
0
~ ❯❯❯

The return status should be 0 -only- when the command/tool has finished successfully, otherwise it should 1 for error, but is suggested to use different numbers to know the specific error happened, for example if someone wants to make a tool like this:

cecli file.c -m "foo bar"
returned="$?"

case "$returned" in
    87)   echo -e "high demand issues, try again in 5 min" ; ;;
    88)   echo -e "connection failed" ; ;;
    ....
esac