Fails when vendor/composer directory removed from build

[KevinBatdorf]

Describe the bug
This was actually a bug in our workflow file but I think exposed an edge case bug with the workflow too

➤ Preparing files...
ℹ︎ Reverting changes in vendor/composer directory
svn: E000002: Can't create directory '/home/runner/svn-***/trunk/vendor/composer': No such file or directory

Steps to Reproduce

1. Have a plugin with /vendor/composer
2. Trigger the workflow and have a change where the /vendor directory has been deleted (so it can't revert /vendor/composer)

https://github.com/10up/action-wordpress-plugin-asset-update/blob/develop/deploy.sh#L134C1-L138C3

Expected behavior
Expected it to fail more gracefully a few lines below