修复白屏BUG、UI 边界溢出 BUG

lib/data/local/models/user_profile.dart

@@ -57,7 +57,7 @@ class UserProfile {
 
   UserProfile copyWith({
     String? nickname,
-    String? avatarLocalPath,
+    Object? avatarLocalPath = _unset,
     String? avatarAssetPath,
     AvatarSource? avatarSource,
     DateTime? updatedAt,
@@ -68,8 +68,12 @@ class UserProfile {
       ..createdAt = createdAt
       ..updatedAt = updatedAt ?? DateTime.now()
       ..nickname = nickname ?? this.nickname
-      ..avatarLocalPath = avatarLocalPath ?? this.avatarLocalPath
+      ..avatarLocalPath = identical(avatarLocalPath, _unset)
+          ? this.avatarLocalPath
+          : avatarLocalPath as String?
       ..avatarAssetPath = avatarAssetPath ?? this.avatarAssetPath
       ..avatarSource = avatarSource ?? this.avatarSource;
   }
 }
+
+const Object _unset = Object();