MM-10791: Don't try and generate thumbnails for non-images/svgs. (#8937)

app/import.go

@@ -1699,11 +1699,13 @@ func (a *App) OldImportFile(timestamp time.Time, file io.Reader, teamId string,
 		return nil, err
 	}
 
+	if fileInfo.IsImage() && fileInfo.MimeType != "image/svg+xml" {
 		img, width, height := prepareImage(data)
 		if img != nil {
 			a.generateThumbnailImage(*img, fileInfo.ThumbnailPath, width, height)
 			a.generatePreviewImage(*img, fileInfo.PreviewPath, width)
 		}
+	}
 
 	return fileInfo, nil
 }