Fix to meet api specification for empty bodies

It should be generally acknowledged that
returning an empty body for context-type
application/json is not a good practice
but some Confluence API endpoints do this
and sadly the chance of Atlassian changing
this is low so we have to deal with it.

Author: m1no

src/publish/confluence/api/index.ts

@@ -381,10 +381,19 @@ export class ConfluenceClient {
     };
   }
 
-  private handleResponse<T>(response: Response) {
+  private async handleResponse<T>(response: Response) {
     if (response.ok) {
       if (response.body) {
-        return response.json() as unknown as T;
+        // Some Confluence API endpoints return successfull calls with no body while using content-type "application/json"
+        // example: https://developer.atlassian.com/cloud/confluence/rest/v1/api-group-content-restrictions/#api-wiki-rest-api-content-id-restriction-byoperation-operationkey-bygroupid-groupid-get
+        // To prevent JSON parsing errors we have to return null for empty bodies and only parse when there is content
+        let data = await response.text();
+
+        if (data === "") {
+          return null as unknown as T;
+        } else {
+          return JSON.parse(data) as unknown as T;
+        }
       } else {
         return response as unknown as T;
       }