Do not abort request when response content-type is malformed

pkg/middlewares/compress/compression_handler.go

@@ -233,8 +233,12 @@ func (r *responseWriter) Write(p []byte) (int, error) {
 	// Disable compression according to user wishes in excludedContentTypes or includedContentTypes.
 	if ct := r.rw.Header().Get(contentType); ct != "" {
 		mediaType, params, err := mime.ParseMediaType(ct)
+		// To align the behavior with the klauspost handler for Gzip,
+		// if the MIME type is not parsable the compression is disabled.
 		if err != nil {
-			return 0, fmt.Errorf("parsing content-type media type: %w", err)
+			r.compressionDisabled = true
+			r.rw.WriteHeader(r.statusCode)
+			return r.rw.Write(p)
 		}
 
 		if len(r.includedContentTypes) > 0 {

pkg/middlewares/compress/compression_handler_test.go

@@ -577,6 +577,11 @@ func Test_ExcludedContentTypes(t *testing.T) {
 			contentType:    "",
 			expCompression: true,
 		},
+		{
+			desc:           "MIME malformed",
+			contentType:    "application/json;charset=UTF-8;charset=utf-8",
+			expCompression: false,
+		},
 		{
 			desc:                 "MIME match",
 			contentType:          "application/json",
@@ -687,6 +692,11 @@ func Test_IncludedContentTypes(t *testing.T) {
 			contentType:    "",
 			expCompression: true,
 		},
+		{
+			desc:           "MIME malformed",
+			contentType:    "application/json;charset=UTF-8;charset=utf-8",
+			expCompression: false,
+		},
 		{
 			desc:                 "MIME match",
 			contentType:          "application/json",