Content-Type fixes in client4.ts and remote_cluster.go (#27887)

Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Miguel de la Cruz <miguel@mcrx.me>

server/public/model/client4.go

@@ -8848,11 +8848,12 @@ func (c *Client4) GenerateRemoteClusterInvite(ctx context.Context, remoteCluster
 	}
 	defer closeBody(r)
 
-	b, err := io.ReadAll(r.Body)
-	if err != nil {
-		return "", nil, NewAppError("GenerateRemoteClusterInvite", "api.read_error", nil, "", http.StatusInternalServerError).Wrap(err)
+	var inviteCode string
+	if err := json.NewDecoder(r.Body).Decode(&inviteCode); err != nil {
+		return "", nil, NewAppError("GenerateRemoteClusterInvite", "api.unmarshall_error", nil, "", http.StatusInternalServerError).Wrap(err)
 	}
-	return string(b), BuildResponse(r), nil
+
+	return inviteCode, BuildResponse(r), nil
 }
 
 func (c *Client4) GetRemoteCluster(ctx context.Context, remoteClusterId string) (*RemoteCluster, *Response, error) {
@@ -8863,7 +8864,9 @@ func (c *Client4) GetRemoteCluster(ctx context.Context, remoteClusterId string)
 	defer closeBody(r)
 
 	var rc *RemoteCluster
-	json.NewDecoder(r.Body).Decode(&rc)
+	if err := json.NewDecoder(r.Body).Decode(&rc); err != nil {
+		return nil, nil, NewAppError("GetRemoteCluster", "api.unmarshall_error", nil, "", http.StatusInternalServerError).Wrap(err)
+	}
 
 	return rc, BuildResponse(r), nil
 }