ianpegg, thanks to your posting I found a rather simple error that needs correction in addition to your patch:
TribeEvents::setNotice( 'events-not-found', sprintf( __('No upcoming events listed under %s. Check out upcoming events for this category or view the full calendar.', 'tribe-events-calendar') . $tax_term ) );
should be:
TribeEvents::setNotice( 'events-not-found', sprintf( __('No upcoming events listed under %s. Check out upcoming events for this category or view the full calendar.', 'tribe-events-calendar') , $tax_term ) );
So dot before $tax_term should obviously be replaced by a colon.
Code at line 250 should be:
if ( is_tax( $tribe->get_event_taxonomy() ) ) {
$tax_term = get_term_by( 'slug', get_query_var( 'term' ), $tribe->get_event_taxonomy());
$tax_term = $tax_term->name;
}