Check if value has start and end dates (#2116)

- FIxes #2115
- You can test it with this PR
GravityKit/Event-Field#63

💾 [Build
file](https://www.dropbox.com/scl/fi/udg5bubiztk0qgoqw7wcu/gravityview-2.27.1-fd80f29b3.zip?rlkey=82pxrbgyelr7wh7999joj2av7&dl=1)
(fd80f29).

includes/widgets/search-widget/templates/search-field-date_range.php

@@ -14,10 +14,10 @@
 
 <div class="gv-search-box gv-search-date gv-search-date-range">
  <?php if ( ! gv_empty( $label, false, false ) ) { ?>
- <label for="search-box-<?php echo esc_attr( $name ) . '-start'; ?>"><?php echo esc_html( $label ); ?></label>
+  <label for="search-box-<?php echo esc_attr( $name ) . '-start'; ?>"><?php echo esc_html( $label ); ?></label>
  <?php } ?>
  <p>
- <input name="<?php echo esc_attr( $name ) . '[start]'; ?>" id="search-box-<?php echo esc_attr( $name ) . '-start'; ?>" type="text" class="<?php echo esc_html( $gravityview_view->atts['datepicker_class'] ?? '' ); ?>" placeholder="<?php esc_attr_e( 'Start date', 'gk-gravityview' ); ?>" value="<?php echo esc_attr( $value['start'] ); ?>">
- <input name="<?php echo esc_attr( $name ) . '[end]'; ?>" id="search-box-<?php echo esc_attr( $name ) . '-end'; ?>" type="text" class="<?php echo esc_html( $gravityview_view->atts['datepicker_class'] ?? '' ); ?>" placeholder="<?php esc_attr_e( 'End date', 'gk-gravityview' ); ?>" value="<?php echo esc_attr( $value['end'] ); ?>">
+ <input name="<?php echo esc_attr( $name ) . '[start]'; ?>" id="search-box-<?php echo esc_attr( $name ) . '-start'; ?>" type="text" class="<?php echo esc_html( $gravityview_view->atts['datepicker_class'] ?? '' ); ?>" placeholder="<?php esc_attr_e( 'Start date', 'gk-gravityview' ); ?>" value="<?php echo esc_attr( $value['start'] ?? '' ); ?>">
+ <input name="<?php echo esc_attr( $name ) . '[end]'; ?>" id="search-box-<?php echo esc_attr( $name ) . '-end'; ?>" type="text" class="<?php echo esc_html( $gravityview_view->atts['datepicker_class'] ?? '' ); ?>" placeholder="<?php esc_attr_e( 'End date', 'gk-gravityview' ); ?>" value="<?php echo esc_attr( $value['end'] ?? '' );; ?>">
  </p>
 </div>