2 failures:
  @19 (⟨6, 0⟩): '{'; expected '![', '$$', '$', '[' or '[^'
    "Here's a paragraph."
  @19 (⟨6, 0⟩): expected token
    "Here's a paragraph."

Final stack:
  (Lean.Doc.Syntax.para
   "para{"
   [(Lean.Doc.Syntax.role
     "{"
     <missing>
     "["
     [(Lean.Doc.Syntax.footnote <missing>)]
     "]")])