improve error message for use inside ns form

[oakmac]

Follow-up to Issue #152 and PR-171:

We should show more details to the user when :use is detected inside of the ns form. For example, we could include the line + column number where we encountered :use and print a few lines above and below the location so that the user can see more context of where the error occurred.

inspiration / ideas

• https://x.com/jeayewilkerson/status/1870536155189715433