added validation for language api response

[PeculiarGoat]

ADO card.

What it says on the tin.

[PeculiarGoat]

@stajs I felt it would be better to collect all of the errors before returning so we can see all of the issues at once. Otherwise it will be like fix a thing, fail a build, fix another thing, fail another build, and so on.

[stajs]

I don't think that's worth the effort. Fixing things in order seems a reasonable expectation and means the code is slightly simplified and the tests can expect a single error for each condition.

[PeculiarGoat]

@stajs kk I'll change it.

[PeculiarGoat]

@stajs sorted!

[josejibin]

LGTM