Important info

• ReSpec version: 28.1.0
• I did a "hard refresh", but it's still busted.

Description of problem

What happened (e.g., it crashed)?:

I have some <aside class="issue"> in the document without a data-number attribute, meaning they're not filed in Github. The <section id=issue-summary> section omits these issues entirely.

Expected behavior (e.g., it shouldn't crash):

Either give an error for github-less issues or (preferred) include them in the summary.