fix(uploader): failed to generate upload token for some file types (#2847) (#2900)

* fix(mime): `mimeType` not assigned to new value when is empty

* fix(mime): add fallback mime type

pkg/filemanager/driver/oss/oss.go

@@ -240,7 +240,7 @@ func (handler *Driver) Put(ctx context.Context, file *fs.UploadRequest) error {
 
 	mimeType := file.Props.MimeType
 	if mimeType == "" {
-		handler.mime.TypeByName(file.Props.Uri.Name())
+		mimeType = handler.mime.TypeByName(file.Props.Uri.Name())
 	}
 
 	// 是否允许覆盖
@@ -450,7 +450,7 @@ func (handler *Driver) Token(ctx context.Context, uploadSession *fs.UploadSessio
 
 	mimeType := file.Props.MimeType
 	if mimeType == "" {
-		handler.mime.TypeByName(file.Props.Uri.Name())
+		mimeType = handler.mime.TypeByName(file.Props.Uri.Name())
 	}
 
 	// 初始化分片上传