Fix issues with the handling of VM creation

virtweb_frontend/src/routes/EditVMRoute.tsx

@@ -10,6 +10,7 @@ import { VMDetails } from "../widgets/vms/VMDetails";
 
 export function CreateVMRoute(): React.ReactElement {
   const snackbar = useSnackbar();
+  const alert = useAlert();
   const navigate = useNavigate();
 
   const [vm] = React.useState(VMInfo.NewEmpty);

virtweb_frontend/src/widgets/vms/VMDetails.tsx

@@ -60,6 +60,7 @@ function VMDetailsInner(
             p.vm.name = v ?? "";
             p.onChange?.();
           }}
+          checkValue={(v) => /^[a-zA-Z0-9]+$/.test(v)}
           size={ServerApi.Config.constraints.name_size}
         />