The builder hit an unexpected error and had to stop. This is a bug in the tool, not something you did.
Your character is safe — it's saved in this browser. Download a backup copy below before you reload, just to be certain.
Still crashing after a reload? The saved character itself may be the cause. Download the
backup above first, then reset to a blank character:
Reporting the bug sends us the technical details below so we can fix it — thank you!