Adding selective error handling

Signed-off-by: Fritz Durchardt <[email protected]>

pkg/vendir/config/lock_config.go

@@ -55,7 +55,10 @@ func NewLockConfigFromBytes(bs []byte) (LockConfig, error) {
 
 func LockFileExists(path string) bool {
 	if _, err := os.Stat(path); err != nil {
-		return false
+		if errors.Is(err, fs.ErrNotExist) {
+			return false
+		}
+		panic(fmt.Errorf("can not stat file '%v': %v", path, err))
 	}
 	return true
 }