fix(ui): modal null error

front/src/ui/composables/useModal.ts

@@ -53,7 +53,7 @@ export const useModal = <T> (
       return flag in query.value && assignment.isOn(query.value[flag])
     },
     set (newValue: boolean) {
-      router.push({
+      router?.push({
         query: {
           ...query.value,
           [flag]: newValue ? assignment.on(null) : undefined
@@ -78,7 +78,7 @@ export const useModal = <T> (
       return typeof flagValue === 'string' ? flagValue : flagValue === null ? '' : flagValue.join(' ')
     },
     set (newValue: string) {
-      router.push({
+      router?.push({
         query: {
           ...query.value,
           [flag]: newValue