Additional check for string presentation of types

[vvscode]

[x] There is an associated issue that is labelled
'Bug' or 'Accepting PRs' or is in the Community milestone
[x] Code is up-to-date with the master branch
[ ] You've successfully run jake runtests locally
[x] You've signed the CLA
[ ] There are new or updated unit tests validating the change

Fixes #12050

[msftclas]

Hi @vvscode, I'm your friendly neighborhood Microsoft Pull Request Bot (You can call me MSBOT). Thanks for your contribution!

This seems like a small (but important) contribution, so no Contribution License Agreement is required at this point. Real humans will now evaluate your PR.

TTYL, MSBOT;