Inspiration taken from https://github.com/leaflet-extras/leaflet-providers/commit/dea786a3219f9cc824b8e96903a17f46ca9a5afc to use the 'old' relative url protocols and to 'upgrade' them at js runtime.
providers.json
var providers = L.TileLayer.Provider.providers;
JSON.stringify(providers, null, " ");
./data-raw/providerNames.R
was re-ran to update to the latest providers
Some providers had their protocols turned into '//'.
L.TileLayer.prototype.initialize
and L.TileLayer.WMS.prototype.initialize
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