Currently the javascript for leaflet_more_maps doesn't use a behavior/attach structure. As a result, when leaflet hasn't (yet) been attached more_maps is throwing errors because the expected leaflet isn't available.
One of the situations where this occurs is when you are trying to make your site GDPR compliant and the javascript for leaflet* is executed at a later time, which doesn't trigger the attachbehaviors automatically.
Needs review
1.0
Code
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It's likely this issue predates Contrib.social: some issue and comment data are missing.