Fix empty heading

src/parse/mod.rs

@@ -285,7 +285,7 @@ fn heading(p: &mut Parser, at_start: bool) {
     while p.eat_if(NodeKind::Eq) {}
 
     if at_start && p.peek().map_or(true, |kind| kind.is_space()) {
-        p.eat_while(|kind| kind.is_space());
+        p.eat_while(|kind| kind == &NodeKind::Space(0));
         markup_line(p);
         marker.end(p, NodeKind::Heading);
     } else {

tests/typ/structure/heading.typ

@@ -1,5 +1,11 @@
 // Test headings.
 
+---
+#show node: heading as text(blue, node.body)
+
+=
+No heading
+
 ---
 // Different number of equals signs.
 

tests/typ/structure/list.typ

@@ -1,5 +1,9 @@
 // Test lists.
 
+---
+-
+No list
+
 ---
 _Shopping list_
 #list(attached: true)[Apples][Potatoes][Juice]