Previously we'd get an unhelpful backtrace like this:
In gnu/build/linux-modules.scm:
184:47 4 (recursive-module-dependencies _ #:lookup-module _)
98:14 3 (module-dependencies _)
85:18 2 (modinfo-section-contents _)
In ice-9/ports.scm:
439:11 1 (call-with-input-file #f #<procedure get-bytevector-al?> ?)
In unknown file:
0 (open-file #f "r" #:encoding #f #:guess-encoding #f)
ERROR: In procedure open-file:
Wrong type (expecting string): #f
builder for `/gnu/store/…-linux-modules.drv' failed with exit code 1
* gnu/build/linux-modules.scm (find-module-file): When MODULE cannot be
found, raise an error instead of returning #f. This is more useful to
the user.