fatal error when using @v4.2

[TobyHFerguson]

Describe the bug
I get the following:

Run tj-actions/changed-files@v4.2
Getting head sha...
fatal: ambiguous argument 'HEAD^1': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
Getting diff...
fatal: ambiguous argument 'HEAD^1': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
Error: Process completed with exit code 128.

To Reproduce
My template:

      - name: Get modified files using defaults
        id: changed-files
        uses: tj-actions/changed-files@v4.2

Expected behavior
That the system would get a list of changed files

Additional context
using ubuntu-latest

[TobyHFerguson]

d'oh - this was because I hadn't included the fetch-depth: 0 in the checkout repo section. You might want to highlight this in the docs, for newbies like me!

[jackton1]

Yeah definitely it's hidden in the example.

[jackton1]

@TobyHFerguson

Updated the https://github.com/tj-actions/changed-files#usage let me know if this needs to be improved Thanks.