How to ignore the error that source file doesn't exist

[Freed-Wu]

How to ignore the error that source file doesn't exist? I know some program's config has include and inlude!, which the latter will ignore error when the file doesn't exist. How to do it in (neo)mutt? It will be useful for share config in different machines.

source XXX

line 34: source: file XXX could not be sourced

I only find ifdef/finish, not true if. Currently, I have to

source `[ -f XXX ] && echo XXX || echo /dev/null`