Show inner exception for library loading error

[dahlia]

Quote an email from Andrew Whalan:

Hi Minhee,

I just had an issue where I mismatched the architectures of imagemagick on windows (64bit) and python (32bit).

I was running python 32bit for compatibility with other libraries and accidently installed the 64bit version of image magick. Because in api.load_library() the exceptions about being unable to load the DLL are just silently squashed before failing with a generic “cannot find library”.

I eventually ran things through a debugger and found the inner exception, but it took quite a while to figure out exactly what was happening.

It might be helpful if you also show the inner exception if it’s due to being unable to load the library for some reason other than it just can’t be found such as permissions or architecture mismatch which the import init reports as “you probably don’t have it installed”.

Hope this makes sense and is helpful!

-Andrew