[Menu] Add null checks for modules on DisposeAsync#4249

vnbaaij merged 1 commit intomicrosoft:devmicrosoft/fluentui-blazor:devfrom

Tyme-Bleyaert:fix/fluent-menu/module-null-on-disposeasyncTyme-Bleyaert/fluentui-blazor:fix/fluent-menu/module-null-on-disposeasyncCopy head branch name to clipboard