Properly check local path for cloud sync

I created a Cloud Sync task long time ago to backup the FreeNAS config (/data/freenas-v1.db), which worked until yesterday.

Now it is not starting and I get the following error:

Error: Traceback (most recent call last):
{{ File "/usr/local/lib/python3.7/site-packages/middlewared/job.py", line 349, in run}}
{{ await self.future}}
{{ File "/usr/local/lib/python3.7/site-packages/middlewared/job.py", line 386, in __run_body}}
{{ rv = await self.method(*([self] + args))}}
{{ File "/usr/local/lib/python3.7/site-packages/middlewared/schema.py", line 949, in nf}}
{{ return await f(*args, **kwargs)}}
{{ File "/usr/local/lib/python3.7/site-packages/middlewared/plugins/cloud_sync.py", line 897, in sync}}
{{ await rclone(self.middleware, job, cloud_sync)}}
{{ File "/usr/local/lib/python3.7/site-packages/middlewared/plugins/cloud_sync.py", line 161, in rclone}}
{{ await middleware.call("zfs.dataset.query"), cloud_sync["path"])}}
{{ File "/usr/local/lib/python3.7/site-packages/middlewared/plugins/cloud_sync.py", line 335, in get_dataset_recursive}}
{{ )[0]}}
{{ IndexError: list index out of range}}

I only added additional Cloud Sync tasks - nothing else was changed.

I assume it has something to do with the path, as when creating an new Cloud Sync task, I can only select path at "/mnt/" downwards!