core: Always raise SizeofError.
core: Always raise SizeofError.

There's an obvious problem here: Stack traces are destroyed by the second
raise. This might be fine for library usage, but it's kind of unfortunate.
Hacks to fix this might come later.

0000-bigtree/construct,gkonstantyno/construct,riggs/construct,mosquito/construct,0000-bigtree/construct,MostAwesomeDude/construct,riggs/construct,mosquito/construct,gkonstantyno/construct,MostAwesomeDude/construct