Fix uncaught exception with anonymous submodules

[david-maison-TrustInSoft]

An exception was raised when analyzing a module with

module _ = struct ... end
(* or *)
module _ = Functor_with_side_effects(X)

Feel free to cherry-pick or modify these commits as you wish.

[fantazio]

Good catch ! Thanks for fixing it.

Out of curiosity, what do you use the 1st pattern for ?

module _ = struct ... end

[david-maison-TrustInSoft]

Good catch ! Thanks for fixing it.

You’re welcome. Thank you as well for developing this tool, it helped us identify some interesting dead code on our side.

Out of curiosity, what do you use the 1st pattern for ?

I don’t use this pattern in real-world use cases; I only used it in the tests because it made the diff smaller since it also triggers the bug in the same way.