further improve errorhandling

add more output to help solving the problem

Author: Chaosmeister

Diff for: vendor/erusev/parsedown-extra/ParsedownExtra.php

@@ -628,20 +628,28 @@ protected function processTag($elementMarkup) # recursive
         $elementMarkup = mb_convert_encoding($elementMarkup, 'HTML-ENTITIES', 'UTF-8');
 
         # http://stackoverflow.com/q/4879946/200145
-        $DOMDocument->loadHTML($elementMarkup, LIBXML_DTDATTR | LIBXML_NONET);
+        $success = $DOMDocument->loadHTML($elementMarkup);
+        $DOMDocument->removeChild($DOMDocument->doctype);
 
         $errors = libxml_get_errors();
         if ($errors)
         {
-            $errormessage = "<h1>htmlparser error:</h1><br>";
+            $errormessage = "<h1>HTML-parser error:</h1><br>";
             foreach ($errors as $error) {
-                $errormessage .= $error->message;
+                $errormessage .= "Line: " . $error->line . " - " . $error->message;
                 $errormessage .= '<br>';
             }
             return $errormessage;
         }
 
-        $DOMDocument->removeChild($DOMDocument->doctype);
+        if (!isset($DOMDocument->firstChild->firstChild->firstChild))
+        {
+            $errormessage = "<h1>General HTML-parser error:</h1><br>";
+            $errormessage .= "Input:<pre><code>" . htmlspecialchars($elementMarkup) . "</code></pre>";
+            $errormessage .= "Output:<pre><code>" . htmlspecialchars($DOMDocument->saveHTML()) . "</code></pre>";
+            return $errormessage;
+        }
+
         $DOMDocument->replaceChild($DOMDocument->firstChild->firstChild->firstChild, $DOMDocument->firstChild);
 
         $elementText = '';

Diff for: vendor/erusev/parsedown/Parsedown.php

@@ -1977,7 +1977,7 @@ static function instance($name = 'default')
     protected $regexHtmlAttribute = '[a-zA-Z_:][\w:.-]*+(?:\s*+=\s*+(?:[^"\'=<>`\s]+|"[^"]*+"|\'[^\']*+\'))?+';
 
     protected $voidElements = array(
-        'area', 'base', 'br', 'col', 'command', 'embed', 'hr', 'img', 'input', 'link', 'meta', 'param', 'source',
+        'area', 'base', 'br', 'col', 'command', 'embed', 'hr', 'img', 'input', 'link', 'meta', 'param', 'source', 'frame'
     );
 
     protected $textLevelElements = array(