Description

I noticed that errcheck was returning an error by running make lint.
It seems to be caused by missing return value checks in a type assertion.

Error return value is not checked (errcheck)

Steps to Reproduce

make lint

What I Did

I addressed the root cause of the errcheck issue by adding conditional branching to the type assertion.

I decided to keep the function signature the same.

Although ignoring the error could be an option to avoid redundant error handling, I decided to handle it properly rather than ignoring it carelessly.

What I confirmed

• The error disappeared with make lint
• The test cases for the changed parts passed

Others

This is my first PR to tbls.
I often use tbls because they are easy to use and useful.
Thanks for tbls. :D