Fix errcheck issue for saml.go file (#28546)

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

server/.golangci.yml

@@ -90,7 +90,6 @@ issues:
         channels/api4/reaction_test.go|\
         channels/api4/remote_cluster.go|\
         channels/api4/role_test.go|\
-        channels/api4/saml.go|\
         channels/api4/scheme.go|\
         channels/api4/scheme_test.go|\
         channels/api4/shared_channel.go|\

server/channels/api4/saml.go

@@ -46,7 +46,9 @@ func getSamlMetadata(c *Context, w http.ResponseWriter, r *http.Request) {
 
 	w.Header().Set("Content-Type", "application/xml")
 	w.Header().Set("Content-Disposition", "attachment; filename=\"metadata.xml\"")
-	w.Write([]byte(metadata))
+	if _, err := w.Write([]byte(metadata)); err != nil {
+		c.Logger.Warn("Error while writing response", mlog.Err(err))
+	}
 }
 
 func parseSamlCertificateRequest(r *http.Request, maxFileSize int64) (*multipart.FileHeader, *model.AppError) {