js: fix OperationQueue error handling

When an exception is raised, `response.json()` may have been called
already. In that case, when accessing `response.text()` in the error
handler, a "Response.text: Body has already been
consumed." error will be raised.

app/javascript/components/TypesDeChampEditor/OperationsQueue.js

@@ -45,7 +45,7 @@ async function handleError({ response, message }, reject) {
     try {
       const {
         errors: [message]
-      } = await response.json();
+      } = await response.clone().json();
       reject(message);
     } catch {
       reject(await response.text());