When called, chrome.tabs.highlight({'tabs': tabId}, function(){}); I get this error:
chrome.tabs.highlight({'tabs': tabId}, function(){});
Unchecked runtime.lastError while running tabs.highlight: No tab at index: 7355.
chrome.tabs.highlight requires a tab index, not a tabId. You can convert the tabId to index using chrome.tabs.get:
chrome.tabs.get(tabId, function(tab) { chrome.tabs.highlight({'tabs': tab.index}, function() {}); });
This function does not accept tab IDs, but instead tab indices (positions in the window)