Clean up errors when yaml is invalid

[NNeast]

This cleans errors when yaml file is invalid

Closes #37

Before raising the PR, here is a check list:

1. have you written unit tests for your code changes?
2. have you run "black -l 79 on_your_changed_files.py"?
3. are you requesting to "dev"?
4. have you updated the change log?
5. do you think that you can understand your changes after 6 month?
   5.1) can someone else understand your changes without your explanation?
6. are you pround of your code changes?
   6.1) do you have the feeling of achievement?

[chfw]

Unit tests please.

Since there is big try catch in main function, do you still need the second one?

[chfw]

I will post a bit more comments after the unit tests are written.

[chfw]

Since there has been new changes in dev branch, please synchronise your fork.

[PrajwalM2212]

Closing this PR as #139 solves this issue