remove unnecessary nesting

Parsedown.php

@@ -916,8 +916,11 @@ class Parsedown
 
                 $Span = $this->$handler($markedExcerpt, $text);
 
-                if (isset($Span))
+                if ( ! isset($Span))
                 {
+                    continue;
+                }
+
                 # The identified span can be ahead of the marker.
 
                 if (isset($Span['position']) and $Span['position'] > $markerPosition)
@@ -946,7 +949,6 @@ class Parsedown
 
                 continue 2;
             }
-            }
 
             $remainder = substr($markedExcerpt, 1);