I suggest you change your approach slightly.
Create a FOREACH container which executes for every occurrence of the file you want to process. It will therefore execute either once or not at all.
Put your processing logic inside the FOREACH container.
The package will complete successfully and do nothing if the file is not found.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.