Confusing error (module is not loaded) when more hsigs provided than -instantiated-with

Steps to reproduce:

1. Create an A.hsig file with signature A where
2. Try to build it with ghc --make A.hsig

Expected: Some error indicating an unexpected signature (you need to specify -instantiated-with

Actual: This error:

[1 of 1] Compiling A[sig]           (.hsig -> .o)
attempting to use module ‘main:A’ (A.hsig) which is not loaded

Trac metadata

Trac field	Value
Version	8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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