name of month on prev and next links

Hi,

I have another problem:) I would like to delete name of month on prev and next links in calendar widget. How can I do that? I changed some code in class-eo-calendar-widget.php, from line 267

$foot = sprintf(
				"<tfoot><tr>
					<td id='eo-widget-prev-month' colspan='3'><a title='%s' href='%s'><span></span></a></td>
					<td class='pad'>?</td>
					<td id='eo-widget-next-month' colspan='3'><a title='%s' href='%s'><span></span></a></td>
				</tr></tfoot>",
				esc_html__( 'Previous month', 'eventorganiser' ),
				add_query_arg( 'eo_month', $last_month->format( 'Y-m' ) ),
				esc_html( eo_format_datetime( $last_month, 'M' ) ),
				esc_html__( 'Next month', 'eventorganiser' ),
				add_query_arg( 'eo_month', $next_month->format( 'Y-m' ) ),
				esc_html(eo_format_datetime( $next_month, 'M' ) )
			);

but it wasn’t work perfectly: https://www.mayyer.pl/p/mdk/beta/

As you can see names are visible but when I click on link prev or next they are disappear. They are back when I reload site.

https://www.ads-software.com/plugins/event-organiser/