fix: return error message

[xhsun]

Description

According to Cmd.Output():

Output runs the command and returns its standard output. Any returned error will usually be of type [*ExitError]. If c.Stderr was nil and the returned error is of type [*ExitError], Output populates the Stderr field of the returned error.

Update how we are returning the error so that we are actually returning the error message

What type of PR is this? (only check one)

• Feature (feat)
• Bug Fix (fix)
• Refactor (refactor)
• Documentation Update (doc)
• Other, please specify:

Does this PR introduce any breaking changes?

• No
• Yes, and this is why:
• I need help determining if there are any breaking changes

Does the PR title type prefix match the selected type?

• Yes
• No, and this is why:
• I need help select the right one

Added/updated tests?

Please keep the code coverage percentage at 80% and above.

• Yes
• No, and this is why: just changing error return
• I need help with writing tests