fix: body used already error fix #340

Author: Ephigenia

lib/httpadapter/fetchadapter.js

@@ -42,10 +42,11 @@ class FetchAdapter {
         if (fullResponse) {
           return res;
         }
+        const rawResponseBody = res.text();
         try {
-          return await res.json();
+          return JSON.parse(rawResponseBody);
         } catch (e) {
-          throw new HttpError(await res.text(), {
+          throw new HttpError(rawResponseBody, {
             code: res.statusCode
           });
         }