'frontend/src/types.ts' を更新

frontend/src/types.ts

@@ -54,8 +54,8 @@ export type Post = {
 
 export type PostTagChange = {
     post:       Post
-    tag:        Tag
+    tag:        Tag | null
-    user?:      User
+    user:       User | null
     changeType: 'add' | 'remove'
     timestamp:  string }