500 error when using a markdown task list item across lines
As reported in #421985 (comment 1632753686), a certain task list item can cause a problem:
- one
- foo
[ ] bar
This causes the error
NoMethodError - undefined method `captures' for nil:NilClass:
lib/banzai/filter/task_list_filter.rb:90:in `call'
lib/banzai/pipeline/base_pipeline.rb:23:in `block (2 levels) in singleton class'