Fix undefined variables (#161)

* fix undefined variables

* Handle _referrer_id notice as well

Author: luizbills

inc/wplf-form-actions.php

@@ -166,8 +166,8 @@ function wplf_email_maybe_implode_serialized_value( $value, $form_id = 0, $form_
 
   if ( is_array( $value ) ) {
     $implode_glue = apply_filters( 'wplf_email_array_field_implode_glue', ', ' );
-    $implode_glue = apply_filters( "wplf_{$form->post_name}_email_array_field_implode_glue", $implode_glue );
-    $implode_glue = apply_filters( "wplf_{$form->ID}_email_array_field_implode_glue", $implode_glue );
+    $implode_glue = apply_filters( "wplf_{$form_name}_email_array_field_implode_glue", $implode_glue );
+    $implode_glue = apply_filters( "wplf_{$form_id}_email_array_field_implode_glue", $implode_glue );
 
     $value = implode( $implode_glue, $value );
   }

inc/wplf-form-validation.php

@@ -119,9 +119,10 @@ function wplf_validate_additional_fields( $return ) {
     }
   }
   $additional_fields = array_filter( $additional_fields ); // get rid of the empty keys
+  $referrer_id = isset( $all_fields['_referrer_id'] ) ? $all_fields['_referrer_id'] : null;
 
   // support archive referrer, do not keep field _referrer_archive_title as a additional field
-  if ( 'archive' === $all_fields['_referrer_id'] && array_key_exists( '_refererr_archive_title', $additional_fields ) ) {
+  if ( 'archive' === $referrer_id && array_key_exists( '_refererr_archive_title', $additional_fields ) ) {
     unset( $additional_fields['_referrer_archive_title'] );
   }