Exception not handled correctly when changing to unknown projection

[prushforth]

Steps to reproduce

Do a build
Load localhost dist/index.html
Copy base osm layer, paste, now have 2 layers
Open devtools, select <mapml-viewer> in elements panel
Change projection="OSMTILE" to projection="FOO"

What happens:

Exception:

Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'latLngToPoint')
at i.project (leaflet-src.js:4095:29)
at i.latLngToLayerPoint (leaflet-src.js:4117:31)
at i._getCenterOffset (leaflet-src.js:4643:17)
at i._tryAnimatedPan (leaflet-src.js:4718:23)
at i.setView (leaflet-src.js:3309:12)
at MapViewer.zoomTo (mapml-viewer.js:993:15)
at mapml-viewer.js:391:18

What should happen:

A user friendly error message should be console logged. (there is no Promise.catch on that block).