Fixes exception handler for file_not_parseable under file_updater and fixes error handler for package not found error

[sachin-sandhu]

What are you trying to accomplish?

Preface: Fixes issues related with Dependabot::SharedHelpers::HelperSubprocessFailed

Issues: Issues as following:

1. Exceptions related with malformed package.json.
2. Unhandled issue when package name is omitted from registry resulting in unhandled exception

Fix:

1. Aligns exception class to be more suitable with file updater class of errors.
2. Adds handler to handle scenario of null package name specified in dependency.

Anything you want to highlight for special attention from reviewers?

How will you know you've accomplished your goal?

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.

[abdulapopoola]

where is this new error thrown? I don't see the changes in this pR