Description
We have some package (in our case @sentry/browser) installed two places in our tree (in our case, two different npm workspaces which npm in its infinite wisdom did not figure out how to deduplicate, although I think this can come about from dependencies-of-dependencies as well). This package exports a class with a protected method. Assigning an instance of one to the other works in TS, but fails in Go, because I guess it didn't deduplicate the package like TS does. (There are also other cases where deduplicating affects behavior, mostly in very complex types, and probably many more where it affects performance.)
Let me know if more details are helpful to repro, it's a bit more ceremony to construct than most repros and it sounded like @jakebailey already knew enough to be aware of the problem, but I can set something up if it's more of an edge case and you need one.