{"action":"created","issue":{"url":"https://api.github.com/repos/handsontable/handsontable/issues/3421","repository_url":"https://api.github.com/repos/handsontable/handsontable","labels_url":"https://api.github.com/repos/handsontable/handsontable/issues/3421/labels{/name}","comments_url":"https://api.github.com/repos/handsontable/handsontable/issues/3421/comments","events_url":"https://api.github.com/repos/handsontable/handsontable/issues/3421/events","html_url":"https://github.com/handsontable/handsontable/issues/3421","id":150085055,"number":3421,"title":"Cannot read property 'tagName' of null at ManualRowMover.checkRowHeader","user":{"login":"IntegerMan","id":5049957,"avatar_url":"https://avatars.githubusercontent.com/u/5049957?v=3","gravatar_id":"","url":"https://api.github.com/users/IntegerMan","html_url":"https://github.com/IntegerMan","followers_url":"https://api.github.com/users/IntegerMan/followers","following_url":"https://api.github.com/users/IntegerMan/following{/other_user}","gists_url":"https://api.github.com/users/IntegerMan/gists{/gist_id}","starred_url":"https://api.github.com/users/IntegerMan/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/IntegerMan/subscriptions","organizations_url":"https://api.github.com/users/IntegerMan/orgs","repos_url":"https://api.github.com/users/IntegerMan/repos","events_url":"https://api.github.com/users/IntegerMan/events{/privacy}","received_events_url":"https://api.github.com/users/IntegerMan/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/handsontable/handsontable/labels/Demo%20needed","name":"Demo needed","color":"0052cc"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":2,"created_at":"2016-04-21T14:06:54Z","updated_at":"2016-04-21T14:33:02Z","closed_at":null,"body":"When I focus a cell in HoT when using the ManualRowMover plugin, I've observed that sometimes I encounter a \"Cannot read property 'tagName' of null at ManualRowMover.checkRowHeader\" error 2 - 4 times in rapid succession. This seems to be more prevalent for columns that I have to scroll into view in order to click and seems to mostly happen on the first time you click a cell, but I don't have 100% accurate repro steps on this.\r\n\r\nLooking over the codebase, it looks like checkRowHeader should probably be defined as:\r\n\r\n    checkRowHeader: function(element) {\r\n      if (element != this.hot.rootElement) {\r\n        var parent = element.parentNode;\r\n\r\n        /* This line is new and addresses the null ref encountered */\r\n        if (parent === null || parent === undefined) return false;\r\n\r\n        if (parent.tagName === 'TBODY') {\r\n          return true;\r\n        }\r\n        return this.checkRowHeader(parent);\r\n      }\r\n      return false;\r\n    }"},"comment":{"url":"https://api.github.com/repos/handsontable/handsontable/issues/comments/212945461","html_url":"https://github.com/handsontable/handsontable/issues/3421#issuecomment-212945461","issue_url":"https://api.github.com/repos/handsontable/handsontable/issues/3421","id":212945461,"user":{"login":"IntegerMan","id":5049957,"avatar_url":"https://avatars.githubusercontent.com/u/5049957?v=3","gravatar_id":"","url":"https://api.github.com/users/IntegerMan","html_url":"https://github.com/IntegerMan","followers_url":"https://api.github.com/users/IntegerMan/followers","following_url":"https://api.github.com/users/IntegerMan/following{/other_user}","gists_url":"https://api.github.com/users/IntegerMan/gists{/gist_id}","starred_url":"https://api.github.com/users/IntegerMan/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/IntegerMan/subscriptions","organizations_url":"https://api.github.com/users/IntegerMan/orgs","repos_url":"https://api.github.com/users/IntegerMan/repos","events_url":"https://api.github.com/users/IntegerMan/events{/privacy}","received_events_url":"https://api.github.com/users/IntegerMan/received_events","type":"User","site_admin":false},"created_at":"2016-04-21T14:33:02Z","updated_at":"2016-04-21T14:33:02Z","body":"In order to do that I'd need 100% reproable steps and I'd need to spend a day scrubbing our logic out of the application, unless you mean a video demo. In that case, we might be able to find time to rip out the fix and try to catch the virtualization bug on video."}}