Show error message if Cesium Ion access token is invalid

[nf-s]

No description provided.

[wibily]

Pete: what is the purpose of showing the message if there's nothing the user can do about it?

[staffordsmith83]

Pete: what is the purpose of showing the message if there's nothing the user can do about it?

There is still a purpose: It will notify the user why the map appears to be broken, so rather than think 'This is a terrible product' they realise that creds need to be updated. The use case is probably mostly for maps that we do not host - the users of those maps can then notify their admin. For example, getting a map that looks like this, there is nothing to indicate to non-technical users that there should be terrain underneath unless we show an error in the UI (not the console).

[staffordsmith83]

Found this in Cesium.ts - this appears to have been written to handle this situation and commented out at some point

terriajs/lib/Models/Cesium.ts

Lines 233 to 252 in 7b67f0a

	//catch Cesium terrain provider down and switch to Ellipsoid
	// terrainProvider.errorEvent.addEventListener(function(err) {
	// console.log('Terrain provider error. ', err.message);
	// if (viewer.scene.terrainProvider instanceof CesiumTerrainProvider) {
	// console.log('Switching to EllipsoidTerrainProvider.');
	// that.terria.viewerMode = ViewerMode.CesiumEllipsoid;
	// if (!defined(that.TerrainMessageViewed)) {
	// that.terria.raiseErrorToUser({
	// title : 'Terrain Server Not Responding',
	// message : '\
	// The terrain server is not responding at the moment. You can still use all the features of '+that.terria.appName+' \
	// but there will be no terrain detail in 3D mode. We\'re sorry for the inconvenience. Please try \
	// again later and the terrain server should be responding as expected. If the issue persists, please contact \
	// us via email at '+that.terria.supportEmail+'.'
	// });
	// that.TerrainMessageViewed = true;
	// }
	// }
	// });

[staffordsmith83]

This is mostly working now, see linked draft PR: #6675
There are still a few errors that need fixing before merging