Can't create VARCHAR column via API

[benhaynes]

From directus created by bensteers : directus/directus#2172

Creating a VARCHAR column via the API reports a SQL error:

POST query to /api/1.1/tables/mytable/columns

Working query

request: {'column_name': 'number', 'data_type': 'INT'}
response: {'meta': {'type': 'item', 'table': 'directus_columns'}, 'data': {'id': 'number', 'name': 'number', 'column_name': 'number', 'type': 'INT', 'column_type': 'int(11)', 'length': 0, 'precision': 10, 'scale': 0, 'sort': 9999, 'default_value': None, 'nullable': True, 'key': '', 'extra': '', 'extra_options': [], 'options': [], 'table_name': 'nodes', 'required': False, 'system': False, 'ui': 'numeric', 'hidden_input': False, 'relationship': None, 'comment': "''", 'relationship_type': None, 'related_table': None, 'junction_table': None, 'junction_key_right': None, 'junction_key_left': None}}

The query with an error

request: {'column_name': 'words', 'data_type': 'VARCHAR'}
response: {'success': False, 'error': {'message': 'Statement could not be executed (42000 - 1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near \'DEFAULT NULL COMMENT "\'\'"\' at line 1)'}, 'code': 0, 'class': 'Zend\\Db\\Adapter\\Exception\\InvalidQueryException', 'file': '/var/www/html/vendor/zendframework/zend-db/src/Adapter/Driver/Pdo/Statement.php', 'line': 244}

Version Info

• Directus version and branch (Or commit hash): 6.4.9
• PHP version: 7.1.17
• MySQL version: Ver 14.14 Distrib 5.5.60, for debian-linux-gnu (x86_64) using readline 6.3
• Web server: (Ex. Apache, nginx or IIS?)
• OS name and version: Debian GNU/Linux 8 (jessie)

Steps to Reproduce

1. create table
2. make the two requests above