MAINT: Do not allow `copyswap` and friends to fail silently
MAINT: Do not allow `copyswap` and friends to fail silently

If these can't do the work that is requested, then we should fail loudly, at least during development.

Really the API of these methods is wrong - they should take a `PyArray_Descr`, not an array.

charris/numpy,simongibbons/numpy,WarrenWeckesser/numpy,anntzer/numpy,mattip/numpy,grlee77/numpy,simongibbons/numpy,numpy/numpy,numpy/numpy,mattip/numpy,mhvk/numpy,jakirkham/numpy,endolith/numpy,mhvk/numpy,pbrod/numpy,charris/numpy,grlee77/numpy,seberg/numpy,madphysicist/numpy,anntzer/numpy,mattip/numpy,anntzer/numpy,jakirkham/numpy,mattip/numpy,mhvk/numpy,simongibbons/numpy,seberg/numpy,seberg/numpy,grlee77/numpy,simongibbons/numpy,simongibbons/numpy,grlee77/numpy,madphysicist/numpy,WarrenWeckesser/numpy,endolith/numpy,pdebuyl/numpy,numpy/numpy,endolith/numpy,rgommers/numpy,madphysicist/numpy,abalkin/numpy,pdebuyl/numpy,rgommers/numpy,pdebuyl/numpy,pbrod/numpy,grlee77/numpy,mhvk/numpy,jakirkham/numpy,jakirkham/numpy,mhvk/numpy,anntzer/numpy,seberg/numpy,pbrod/numpy,jakirkham/numpy,pbrod/numpy,pbrod/numpy,charris/numpy,rgommers/numpy,pdebuyl/numpy,endolith/numpy,madphysicist/numpy,numpy/numpy,charris/numpy,WarrenWeckesser/numpy,rgommers/numpy,abalkin/numpy,WarrenWeckesser/numpy,abalkin/numpy,madphysicist/numpy,WarrenWeckesser/numpy