fix(prejoin) Check for valid url for prejoin (#13468)

- `getPropertyValue` calls `parseUrlParam` with the connection URL from store, which is not yet defined

react/features/base/util/parseURLParams.ts

@@ -25,6 +25,10 @@ export function parseURLParams(
         url: URL | string,
         dontParse = false,
         source = 'hash') {
+    if (!url) {
+        return {};
+    }
+
     if (typeof url === 'string') {
         // eslint-disable-next-line no-param-reassign
         url = new URL(url);