>I think Guile could report a warning if a nonexistent variable is 
>exported as the cause of this kind of errors may be difficult to find in 
>a large program.

During compilation, code is analysed and IIRC there is a warning for unbound variables. (I don’t know if warning is the default though.) Large program should be compiled, so they would get the warning.

So, just compile your modules and you should get warnings for the modules.
(I’m not sure about this particular (export this that) case – is it defining ‘this’ as ‘that’, or is it some kind of symbolic reference that can be created even if the target doesn’t exist? If the latter, maybe that’s not checked for for this warning – I don’t know.)

(Perhaps compilation actually happened, autocompilation is the default though it can be disabled – I don’t know if warnings are enabled for autocompiled dependencies though.)

Best regards,
Maxime Devos