Notice: Trying to access array offset on value of type bool

Is there any reason a revision as critical as this is still not being pushed to 7.x-3.x branch? Is the 7.x version now on permanent "use the dev version" status?

This issue is still in the current dev version from 4 Feb 2021. Only the notice message is slightly different (line 441 instead of 431):

Notice: Trying to access array offset on value of type bool in calendar_plugin_row->render() (line 441 of /home/icpdrobs/danubis-icpdr-org/sites/all/modules/contrib/calendar/includes/calendar_plugin_row.inc).

So, the current code still accesses $items[$delta] which is false because the previous call to field_get_items did not get a result. This happens (at least in my case) when there are multiple date fields used in the contextual filter of the View, i.e. a calendar with more than one node type where the names of the date fields are different.
I used the fix in #5 and it gets away with the notice message and the View display works fine (at least in my case).