I stashed a few hours worth of changes.

But when I went to apply them again (on the same branch – happens to be a local branch), I get the following error – this has cost me a lot of changes:

git -c diff.mnemonicprefix=false -c core.quotepath=false stash apply stash@

fatal: ambiguous argument 'stash@0': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] – [<file>...]'

Completed with errors, see above.