Using WMS Layers as basemap with BasemapToggle (or BasemapGallery) and then trying to switch to a different basemap results in a error (and a hanging browser)
#load() Failed to load layer (title: 'undefined', id: 'undefined') TypeError: Cannot read property 'sublayers' of undefined
at WMSLayer.js:5
at Array.forEach (<anonymous>)
at r (WMSLayer.js:5)
at Object.b.readSublayers (WMSLayer.js:9)
at Object.n (init.js:472)
at Object.e.read (init.js:982)
at Object.l (init.js:225)
at init.js:1018
at Object.f.readLoadable (init.js:473)
at Object.e.read (init.js:1018)
This is the same error message as an identified bug with WMS layers: Possible bug :WMSLayer in 4.4 version adding multiple WMSLayers to map