The Date::time_ago() seems to break (timing out) if your timestamp variable passed to it is empty.
ErrorException [ Error ]: Maximum execution time of 30 seconds exceeded
On line 182 where it's checking for if it's null also need to check if the value is empty.
Bug reported on the forums aren't fixed, that's what the issues on Github are for unless someone around here makes the effort to fix & pull-request. We core devs make a point of not accepting bugs here because there's no good way to track everything if we would.