Catch the contract execution errors, and return an error msg to the user

[bchamagne]

Description

Catch contract execution error, so the worker does not crash.
We can't provide a detailed error message to the user because it is an erlang error message based on the code we generated after AST manipulation. We might be able to get the line number, I'll create an issue (#964) about it.

This PR is based on branch pr/netbox/802 which is the following PR: #802. Once it is merged, we will need to change the base branch.

Fixes #919

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

tested with manual contract execution & added unit tests

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules