lib-storage: Remove user namespaces on hook error

If there is a hook error during namespaces added
remove the namespaces from user. This avoids attempts
to use the namespaces later on without proper initialization.

src/lib-storage/mail-namespace.c

@@ -370,26 +370,30 @@ int mail_namespaces_init_finish(struct mail_namespace *namespaces,
 	if (namespaces->user->autocreated) {
 		/* e.g. raw user - don't check namespaces' validity */
 	} else if (!namespaces_check(namespaces, error_r)) {
-		*error_r = t_strconcat("namespace configuration error: ",
-				       *error_r, NULL);
-		while (namespaces != NULL) {
-			ns = namespaces;
-			namespaces = ns->next;
-			mail_namespace_free(ns);
-		}
-		return -1;
+		namespaces->user->error =
+			t_strconcat("namespace configuration error: ",
+				    *error_r, NULL);
 	}
-	mail_user_add_namespace(namespaces->user, &namespaces);
 
-	T_BEGIN {
-		hook_mail_namespaces_created(namespaces);
-	} T_END;
+	if (namespaces->user->error == NULL) {
+		mail_user_add_namespace(namespaces->user, &namespaces);
+		T_BEGIN {
+			hook_mail_namespaces_created(namespaces);
+		} T_END;
+	}
 
 	/* allow namespace hooks to return failure via the user error */
 	if (namespaces->user->error != NULL) {
+		namespaces->user->namespaces = NULL;
 		*error_r = t_strdup(namespaces->user->error);
+		while (namespaces != NULL) {
+			ns = namespaces;
+			namespaces = ns->next;
+			mail_namespace_free(ns);
+		}
 		return -1;
 	}
+
 	namespaces->user->namespaces_created = TRUE;
 	return 0;
 }