Corrupted magicbytes

[SimonDanisch]

Right now this happens:

f = "test.nrrd" #empty file
load(f) 
#ERROR: No load function defined for format FileIO.DataFormat{:UNKNOWN} with filename test.nrrd
save(f) 
#ERROR: No save function defined for format FileIO.DataFormat{:UNKNOWN} with filename test.nrrd

For load we should probably fall back to the file ending or have something like DataFormat{:NRRD_CORRUPTED}.
For save it should probably just work and overwrite it. Or do we want to warn the user and make them use e.g. save! for overwriting?!

[timholy]

It already does:

FileIO.jl/src/query.jl

Lines 246 to 250 in cdffe63

	if (length(len) == 1 && all(x->x==0, len)) || !isfile(filename)
	# If there are no magic bytes, trust the extension
	# Also, if we're about to create the file, it won't exist yet
	return File{DataFormat{sym}}(filename)
	end

. But nothing will happen if the format hasn't been registered.

[SimonDanisch]

But not if there is an empty file with the name, as isfile becomes true...

[timholy]

Oh, I see. Sure, we should fall back on the extension more readily, then.

[timholy]

I think this is fixed.