fix: adds an error route for object calls with ?uploads query arg

Fixes #1597

S3 returns a specific error when calling an object GET operation (e.g., `bucket/object/key?uploads`) with the `?uploads` query parameter. It’s not the standard `MethodNotAllowed` error. This PR adds support for handling this specific error route.

s3err/s3err.go

@@ -123,6 +123,7 @@ const (
 	ErrInvalidAccessKeyID
 	ErrRequestNotReadyYet
 	ErrMissingDateHeader
+	ErrGetUploadsWithKey
 	ErrInvalidRequest
 	ErrAuthNotSetup
 	ErrNotImplemented
@@ -515,6 +516,11 @@ var errorCodeResponse = map[ErrorCode]APIError{
 		Description:    "AWS authentication requires a valid Date or x-amz-date header.",
 		HTTPStatusCode: http.StatusBadRequest,
 	},
+	ErrGetUploadsWithKey: {
+		Code:           "InvalidRequest",
+		Description:    "Key is not expected for the GET method ?uploads subresource",
+		HTTPStatusCode: http.StatusBadRequest,
+	},
 	ErrInvalidRequest: {
 		Code:           "InvalidRequest",
 		Description:    "Invalid Request.",