When rendering a view using Fullcalendar style plugin, the settings get double-processed for some reason, resulting in a flattened structure (e.g. $settings['options']['plugins'][0] becomes $settings[0]). Also, any undefined settings (i.e. settings left blank in the Views UI) cause a PHP notice.
Attached patch fixes above issues, by adding a 'processed' flag to settings and skipping processing if set.
Closed: outdated
2.0
Code
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
I've volunteered to help clean up the FullCalendar issue queue. As part of that effort I'm closing issues open for unsupported versions of the module as "Closed (outdated)".
If this issue is still relevant for version 3.x of FullCalendar, then feel free to re-open it and update the issue version number.