Fix leaving a group

There's still an issue because the call is made twice, but at least it
works

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/src/components/core/CustomDialog.vue

@@ -137,7 +137,9 @@ const close = () => {
  */
 const cancel = (source: string) => {
   emit("cancel", source);
-  props.onCancel?.apply(null, [source]);
+  if (props?.onCancel) {
+    props?.onCancel(source);
+  }
   close();
 };
 </script>

js/src/views/Group/GroupView.vue

@@ -806,15 +806,20 @@ const openLeaveGroupModal = async (): Promise<void> => {
       "Are you sure you want to leave the group {groupName}? You'll loose access to this group's private content. This action cannot be undone.",
       { groupName: `<b>${displayName(group.value)}</b>` }
     ),
-    onConfirm: () => leaveGroup(),
+    onConfirm: leaveGroup,
     confirmText: t("Leave group"),
     cancelText: t("Cancel"),
   });
 };
 
+const {
+  mutate: leaveGroupMutation,
+  onError: onLeaveGroupError,
+  onDone: onLeaveGroupDone,
+} = useLeaveGroup();
+
 const leaveGroup = () => {
-  const { mutate: leaveGroupMutation, onError: onLeaveGroupError } =
-    useLeaveGroup();
+  console.debug("called leaveGroup");
 
   const [groupFederatedUsername, currentActorId] = [
     usernameWithDomain(group.value),
@@ -837,13 +842,17 @@ const leaveGroup = () => {
       ],
     }
   );
+};
 
-  onLeaveGroupError((error: any) => {
+onLeaveGroupError((error: any) => {
   if (error.graphQLErrors && error.graphQLErrors.length > 0) {
     notifier?.error(error.graphQLErrors[0].message);
   }
-  });
-};
+});
+
+onLeaveGroupDone(() => {
+  console.debug("done");
+});
 
 const { mutate: followGroupMutation, onError: onFollowGroupError } =
   useMutation(FOLLOW_GROUP, () => ({

lib/graphql/resolvers/group.ex

@@ -341,6 +341,10 @@ defmodule Mobilizon.GraphQL.Resolvers.Group do
       {:group, nil} ->
         {:error, dgettext("errors", "Group not found")}
 
+      # Actions.Leave.leave can also return nil if the member isn't found. Probably something to fix.
+      nil ->
+        {:error, dgettext("errors", "Member not found")}
+
       {:error, :is_not_only_admin} ->
         {:error,
          dgettext("errors", "You can't leave this group because you are the only administrator")}