Add stronger assertions to rake migration tasks to make sure the user is providing a numeric VERSION
An empty string was getting converted to version = 0. This would in turn pass the presence check.

Address linting warning

Add test for rake task and refactor code to meet expectations
In particular passing VERSION=0 should not raise an error.

Addressed Comments for PR #28485. Trimmed empty lines + change of wording for error message

Adjust test for change of wording in error message

Change condition to follow rails idioms