the caller just checked that symbol is defined, so symbol && shouldn't be needed.

Or it should be Symbol | undefined then

what's an example for this case? it looks like the const B = function ... case in the new test file, but I expected that to be imported from a new, third file instead of just being in the original file.

The const A = case tests the from an external file, while the const B = case tests the use locally. Both cases are relevant. Are you talking about a third case where we import something re-exported from a third file?

Does line 16096 handle the const A = test (external) and 16099 handle the const B = test (local)? The two tests differ in syntax, so I thought the difference in the two cases in getJavascriptClassType was syntactic, and that both needed to come from external files. I guess that's wrong, and the difference is external vs local?

Line 16096 handles the case where symbol refers directly (globally or within the same file) to a function or a variable declaration whose initializer is a function.

Line 16099 handles the case where symbol refers indirectly to a function or variable declaration whose initializer is a function. This is usually the case for imports like const C = require("./c") or const { C } = require("./c"), but also cases like const C = B where B is also local and is a function or variable declaration whose initializer is a function.