OK, I think I know what happened... We had
jsreport.Types 2.2.7 installed, but we did not have
jsreport.Shared installed at all (it says "internal" and it seems that it worked fine without it being explicitly installed). I don't know how package dependencies are configured - but it looks like we had earlier version reference Shared 2.0.0; and after we upgraded Types - it continued to reference 2.0.0, rather than force upgrade to 2.0.1
You are right - we could install Shared 2.0.1 explicitly (which we just did, and it indeed works fine), or (what we did) we reverted Types to 2.2.6 that continued to use Shared 2.0.0 implicitly.
Thank you, it's all good now!