Display error if JS fails to load. Fixes #404

index.html

@@ -386,5 +386,15 @@
 
     <main id="app" aria-hidden="true"></main>
     <script type="module" src="/src/main.ts"></script>
+
+    <script>
+        window.addEventListener('load', () => {
+            if(!window.liveAtlasLoaded) {
+                document.getElementById('splash__error').setAttribute('aria-hidden', 'false');
+                document.getElementById('splash__error-message').innerText = 'Required LiveAtlas files are missing or failed to load.\nPlease reinstall LiveAtlas.';
+                document.getElementById('splash__spinner').style.visibility = 'hidden';
+            }
+        });
+    </script>
   </body>
 </html>

src/index.d.ts

@@ -47,6 +47,7 @@ declare global {
 	// noinspection JSUnusedGlobalSymbols
 	interface Window {
 		liveAtlasConfig: LiveAtlasGlobalConfig,
+		liveAtlasLoaded: ?boolean,
 	}
 
 	declare const process : {

src/main.ts

@@ -59,6 +59,7 @@ registerMapProvider('squaremap', Pl3xmapMapProvider);
 registerMapProvider('overviewer', OverviewerMapProvider);
 
 const config = window.liveAtlasConfig;
+window.liveAtlasLoaded = true;
 
 try {
 	config.servers = loadConfig(config);