Assertion failure in `parse_pagenode`

On file 037c2b16f2f7517f835320faf628c688237619b478f5510a65dd17cac0c265b9 from Eval 3 Universe B:

parse_pagenode: Assertion 'contents->token_type == (HTokenType)TT_SEQUENCE' failed.

Discovered with !29 (merged).