FIX: supports bare <li> when converting html to markdown

lib/html_to_markdown.rb

@@ -114,7 +114,7 @@ class HtmlToMarkdown
 
   def visit_li(node)
     parent = @stack.reverse.find { |n| n.name[/ul|ol|menu/] }
-    prefix = parent.name == "ol" ? "1. " : "- "
+    prefix = parent&.name == "ol" ? "1. " : "- "
     @stack << Block.new("li", prefix, "  ")
     traverse(node)
     @markdown << format_block
@@ -209,7 +209,6 @@ class HtmlToMarkdown
   end
 
   def format_block
-
     lines = @stack[-1].markdown.each_line.map do |line|
       prefix = @stack.map { |b| b.opened ? b.body : b.head }.join
       @stack.each { |b| b.opened = true }

spec/components/html_to_markdown_spec.rb

@@ -181,6 +181,10 @@ describe HtmlToMarkdown do
     )).to eq("- Fruits\n  - 🍏\n  - 🍐\n  - 🍌\n- Vegetables\n  - 🍆\n  - 🍅\n  - 🍄")
   end
 
+  it "supports bare <li>" do
+    expect(html_to_markdown("<li>I'm alone</li>")).to eq("- I'm alone")
+  end
+
   it "supports <pre>" do
     expect(html_to_markdown("<pre>var foo = 'bar';</pre>")).to eq("```\nvar foo = 'bar';\n```")
     expect(html_to_markdown("<pre><code>var foo = 'bar';</code></pre>")).to eq("```\nvar foo = 'bar';\n```")