Fixed a bug with template rendering.

wagtail/contrib/table_block/__init__.py

@@ -74,7 +74,7 @@ class TableBlock(FieldBlock):
 
     def render(self, value):
         template = getattr(self.meta, 'template', None)
-        if template:
+        if template and value:
             table_header = value['data'][0] if value.get('data', None) and len(value['data']) > 0 and value.get('first_row_is_table_header', False) else None
             first_col_is_header = value.get('first_col_is_header', False)
             context = {