Fix copy._func not existing when copying and print the error when downloading

[kelvinburke]

I am not totally sure why copy.func_ doesn't exist after standard_dcp, but this fix works, because we only need to delete it if we don't have it. This was stopping dcp(project) from working

Had to do a little wrangling of the error message for the download because it was a blob so we have to convert to json - which is harder than it sounds - but it works now

Merging this will "reupdate" to the new version