parent fixes

index.mjs

@@ -517,7 +517,7 @@ function buildAST(md, mdTags=syntax, offset=0, tree={tag: 'root'}, stack=[]){
             children.push(newNode)
 
             newNode.children = buildAST(listMD, mdTags).children
-            newNode.children.forEach(item => item.parent = currentNode)
+            newNode.children.forEach(item => typeof item === 'object' &&  item.parent = currentNode)
 
             offset = newNode.endOffset = currentNode.endOffset = endMatch.index + offset
         }