Steps to reproduce the issue

I have a custom module with a SQL form field

<config>
    <fields name="params">
        <fieldset name="basic">
            <field
                   name="grid_id"
                   type="sql"
                   default="1"
                   label="Select an imagegrid"
                   query="SELECT grid_name AS value, grid FROM #__imagegrid" />
        </fieldset>
    </fields>
</config>

Expected result

No error

Actual result

Notice: Undefined property: stdClass::$grid_id in libraries/joomla/form/fields/sql.php on line 308

System information (as much as possible)

Joomla 3.7.4
Apache
MySQL

Additional comments

Is this a problem with my module or something in Joomla core? Thanks