> when is this line invoked? I tried a 3rd party package with documentation to modules that dne and vice versa but I didn't notice this exception.

On current master, if I extract erikvold-menuitems-jplib-5108038.zip under packages and run cfx docs, I get this error.

> Also I don't think we can get to this line for 3rd party packages because of the change in line 66, so I don't think this line needs to change.

In theory, right, we can't. But if for some reason we do (for example, because a modules isn't identifiable as a third party module, but does not use the expected mapping between module source and module doc) then it's almost certainly better for the doc generator to return some empty metadata, than to have cfx docs be permanently unusable. Throwing an exception is almost certainly the wrong thing to do here, I think.