fix(npf): check if vectors has element before accessing them

src/convert/npf.rs

@@ -78,9 +78,11 @@ impl<'a> TryFrom<&'a Node<'a, RefCell<Ast>>> for objects::Post {
             }
             NodeValue::BlockQuote => {
                 let mut p = Self::try_from(node.children())?.join_content("\n\n");
+                if p.content.len() > 0 {
                     if let BlockValue::Text(ref mut t) = &mut p.content[0] {
                         t.subtype = Some(BlockTextSubtype::Indented);
                     }
+                }
                 Ok(p)
             }
             NodeValue::Text(t) => {

src/convert/npf/objects_post.rs

@@ -84,10 +84,12 @@ impl Post {
             })
             .flatten()
             .collect::<Vec<_>>();
+        if self.content.len() > 0 {
             let block = &mut self.content[0];
             if let BlockValue::Text(ref mut t) = block {
                 t.text = String::from(t.text.strip_suffix(sep).unwrap_or(&t.text));
             }
+        }
         self
     }
     pub fn for_each_content<F>(mut self, f: F) -> Self