simplifying if-else chains to switches (#6208)

cmd/object-api-errors.go

@@ -375,20 +375,14 @@ func (e BackendDown) Error() string {
 
 // isErrIncompleteBody - Check if error type is IncompleteBody.
 func isErrIncompleteBody(err error) bool {
-	switch err.(type) {
-	case IncompleteBody:
-		return true
-	}
-	return false
+	_, ok := err.(IncompleteBody)
+	return ok
 }
 
 // isErrObjectNotFound - Check if error type is ObjectNotFound.
 func isErrObjectNotFound(err error) bool {
-	switch err.(type) {
-	case ObjectNotFound:
-		return true
-	}
-	return false
+	_, ok := err.(ObjectNotFound)
+	return ok
 }
 
 // isInsufficientReadQuorum - Check if error type is InsufficientReadQuorum.