Fix regression in fetchConfiguration

src/App.tsx

@@ -127,7 +127,6 @@ export class App extends React.Component<IAppProps> {
  */
 export async function fetchConfiguration(): Promise<Configuration> {
   const url = `${import.meta.env.VITE_API_URL}`;
-
   // The test library cannot use the Fetch API
   // @ts-ignore
   if (window.fetch) {
@@ -138,15 +137,13 @@ export async function fetchConfiguration(): Promise<Configuration> {
         response.json()
       ) as Configuration;
   }
-
-  return new Promise((resolve, reject) => {
+  return new Promise((resolve) => {
     const xhr = new XMLHttpRequest();
     xhr.open('POST', url, true);
     xhr.onreadystatechange = function() { // Call a function when the state changes.
       if (xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {
         resolve(JSON.parse(this.responseText));
       }
-      reject(xhr.responseText);
     };
     xhr.send();
   });