fix: Additional safety around detecting functions in HTML output

Author: tmcw

src/default_theme/index.js

@@ -13,6 +13,7 @@ function isFunction(section) {
   return (
     section.kind === 'function' ||
     (section.kind === 'typedef' &&
+      section.type &&
       section.type.type === 'NameExpression' &&
       section.type.name === 'Function')
   );