Show an error when the browser does not support WebRTC

src/main.tsx

@@ -39,12 +39,21 @@ initRageshake();
 
 console.info(`matrix-video-chat ${import.meta.env.VITE_APP_VERSION || "dev"}`);
 
+let fatalError: Error | null = null;
+
 if (!window.isSecureContext) {
-  throw new Error(
+  fatalError = new Error(
     "This app cannot run in an insecure context. To fix this, access the app " +
       "via a local loopback address, or serve it over HTTPS.\n" +
       "https://developer.mozilla.org/en-US/docs/Web/Security/Secure_Contexts"
   );
+} else if (!navigator.mediaDevices) {
+  fatalError = new Error("Your browser does not support WebRTC.");
+}
+
+if (fatalError !== null) {
+  ReactDOM.render(fatalError.message, document.getElementById("root"));
+  throw fatalError; // Stop the app early
 }
 
 if (import.meta.env.VITE_CUSTOM_THEME) {