I think the reason why the game crashed is because when an entity goes into the void, it usually kills it. but, when riding the entity in the void, the game get's confused and crashes.
I think when the entity dies in the void, the game should dismount you from the entity.
Linked issues
Attachments
Comments 3

Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-37670.
It has been linked to this report. If you have additional information, please add it to the duplicated report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-37670.
It has been linked to this report. If you have additional information, please add it to the duplicated report.
Please search before reporting, as it's likely that one exists already.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki