Ensure input file exists before copying

Resolves: #33

Signed-off-by: Keshav Priyadarshi <git@keshav.space>

Author: keshav-space

action.yml

@@ -165,7 +165,7 @@ runs:
           else
             echo "Input directory '$SOURCE_PATH' is empty, nothing to copy."
           fi
-        else
+        elif [[ -f "$SOURCE_PATH" ]]; then
           echo "Copying file: $SOURCE_PATH → $DESTINATION_PATH"
           cp "$SOURCE_PATH" "$DESTINATION_PATH"
         fi