added braces to escapable characters

src/Parser.php

@@ -170,7 +170,8 @@ class Parser {
 				TokenType::BACKTICK,
 				TokenType::ASTERISK,
 				TokenType::LBRACKET,
-				TokenType::BANG
+				TokenType::BANG,
+				TokenType::LBRACE
 			])) {
 				$this->consume()->data; // backslash
 				$buffer .= $this->consume()->data;
@@ -344,7 +345,6 @@ class Parser {
 	private function buildParagraph(array $elms) : void {
 		if (count($elms) < 1)
 			return;
-
 		$elm = $this->document->createElement("p");
 		$i   = 0;
 		foreach ($elms as $node) {
@@ -375,6 +375,7 @@ class Parser {
 		}
 		$elm = $this->document->createElement("h".$level);
 		foreach ($this->parseText() as $node)
+			if ($node instanceof DOMNode)
 				$elm->appendChild($node);
 		$this->document->appendChild($elm);
 	}