Add exception handler for invalid tar files

[oliverli]

Description

Wrap Archive.get_file_hierarchy in an exception handler, and return "Could not read archive" if an exception is thrown

Motivation and Context

Due to changes in lib/archive.rb, some invalid tar files will result in an ArgumentError being thrown, which causes a 500 error since the exception is not handled

How Has This Been Tested?

Tested with this submission

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation, which is located at Autolab Docs
• I have updated the documentation accordingly, included in this PR

[fanpu]

Could replicate difference between master and this branch, code looks good too, LGTM