Fix errcheck issue in handlers.go (#28794)

server/.golangci.yml

@@ -261,7 +261,6 @@ issues:
         channels/utils/fileutils/fileutils_test.go|\
         channels/utils/license_test.go|\
         channels/utils/subpath_test.go|\
-        channels/web/handlers.go|\
         channels/web/oauth.go|\
         channels/web/oauth_test.go|\
         channels/web/response_writer_wrapper_test.go|\

server/channels/web/handlers.go

@@ -450,7 +450,9 @@ func (h Handler) handleContextError(c *Context, w http.ResponseWriter, r *http.R
 	if IsAPICall(c.App, r) || IsWebhookCall(c.App, r) || IsOAuthAPICall(c.App, r) || r.Header.Get("X-Mobile-App") != "" {
 		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(c.Err.StatusCode)
-		w.Write([]byte(c.Err.ToJSON()))
+		if _, err := w.Write([]byte(c.Err.ToJSON())); err != nil {
+			c.Logger.Error("Failed to write error response", mlog.Err(err))
+		}
 	} else {
 		utils.RenderWebAppError(c.App.Config(), w, r, c.Err, c.App.AsymmetricSigningKey())
 	}