Update tbl2asn.rb

[TaoLee0510]

• Have you followed the guidelines for contributing?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source FORMULA, where FORMULA is the name of the formula you're submitting?
• Does your build pass brew audit --strict FORMULA (after doing brew install FORMULA)?

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[TaoLee0510]

error fixes