Vim + Fish = "E484: Can't open file /tmp/vRDNVqe/0" error

If you get errors in Vim like:

E484: Can't open file /tmp/vRDNVqe/0

It's because you probably are using the Fish shell. The fix is simple, just tell Vim in the ~/.vimrc config file to use a different shell for running commands:

set shell=/bin/sh