Thanks for the report! It's a known bug actually, so no worries, the next demo will resolve these issues.
Currently there are a few known places where this bug can be reproduced. It's because the character won't jump at all when it's not standing on stable ground, so it gets stuck when it falls in a tight gap. It was originally done this way to avoid being able to spam the jump button to climb steep surfaces. I rewrote a large portion of the character controller since, so you shouldn't encounter that bug anymore in the next updates.