Tables not fully compatible with GFM format

[raulbocanegra]

Describe the bug
Tables not fully compatible with Github Flavoured Markdown format. It returns a paragraph instead of table.

To Reproduce
Extracted from GFM example 205

| abc | def |
| --- | --- |

Converting the markdown above returns:

<p>| abc | def |
| --- | --- |</p>

Expected behavior

<table>
<thead>
<tr>
  <th>abc</th>
  <th>def</th>
</tr>
</thead>
</table>

Debug info
Version of library being used: 2.5.1

Any extras being used: tables

Additional context
Add any other context about the problem here.