Fix none-node_module imports of built ts files

[Pajn]

fixes #667

[johnnyreilly]

This looks good! It's a minor change and the existing tests still pass with it which is good.

Generally it's good to have a test to cover changed behaviour to prevent regressions in the future.
Unfortunately it looks tricky to create a test for this will be hard given the difficulties creating a repro.

I think it makes sense to merge and when I release this I'll keep my eyes open for anyone having issues. Hopefully there won't be any.

Thanks so much for drilling into this and coming up with a solution!

[johnnyreilly]

Published with 3.1.1 - thanks so much!