Hi,

org-babel-detangle is an interactive command but
M-x org-babel-detangle always replies "Detangled 0 code blocks"
This patch makes org-babel-detangle prompt for a source code file.

Obviously, I got bitten by this.

The patch contains
(user-error "Source code file does %S not exist" source-code-file)
so it may break code that uses org-babel-detangle in a loop.

I prefer an user-error, but others may not.

Regards -- Gerard