WIP: In GHCi don't defer the error message `Could not find module`. (Fixes #11596)
When should GHC report the error message Could not find module?
There are 2 options:
- at the time GHC tries to read the file with the module code.
- at the time GHC tries to compile code from the missing input file.
The patch ff3f918d for #11256 (closed) changed from option 1. to option 2.
As a side effect we got #11596: A GHCi :reload command gets confused if an input file has been deleted:
GHCi doesn't report the error on a :reload command, however the evaluation of the next
expression fails with a very obscure error message!
Therefore this patch uses again option 1. for GHCi, and continues to use option 2. for GHC.