strong-unclosed-inner-survives

An unclosed ** is a Class 1 (symmetric) opener: only the opener degrades to Text; constructs after it parse normally

§9.4.1 · source

Input

**a __b__ c

Output AST

- type: Paragraph
  children:
    - type: Text
      value: "**a "
    - type: Emphasis
      children:
        - type: Text
          value: b
    - type: Text
      value: " c"