delete PageTagRelation when the page is deleted completely

src/server/models/page.js

@@ -1157,6 +1157,7 @@ module.exports = function(crowi) {
     const Bookmark = crowi.model('Bookmark');
     const Attachment = crowi.model('Attachment');
     const Comment = crowi.model('Comment');
+    const PageTagRelation = crowi.model('PageTagRelation');
     const Revision = crowi.model('Revision');
     const pageId = pageData._id;
     const socketClientId = options.socketClientId || null;
@@ -1166,6 +1167,7 @@ module.exports = function(crowi) {
     await Bookmark.removeBookmarksByPageId(pageId);
     await Attachment.removeAttachmentsByPageId(pageId);
     await Comment.removeCommentsByPageId(pageId);
+    await PageTagRelation.findOneAndRemove({ relatedPage: pageId });
     await Revision.removeRevisionsByPath(pageData.path);
     await this.findByIdAndRemove(pageId);
     await this.removeRedirectOriginPageByPath(pageData.path);