Fix Combiner referencing function on 'null' value.

readme.txt

@@ -259,6 +259,7 @@ You can hide a row by adding a hook. Checkout this example:
 = develop =
 
 * Enhancement: Nested forms can now also export entry meta values.
+* Fixed: Nested form values could cause an exception.
 
 = 2.3.7 on January 17, 2025 =
 

src/Transformer/Combiner.php

@@ -78,7 +78,8 @@ public function parseEntry( array $fields, array $entry ): void {
 				return $output;
 			}, '' );
 
-			$gf_field = array_filter( $values ) ? reset( $values )->getField() : new GF_Field();
+			$non_empty_values = array_filter( $values );
+			$gf_field         = $non_empty_values ? reset( $non_empty_values )->getField() : new GF_Field();
 
 			$combined_row[ $column ] = new StringValue( $combined, $gf_field );
 		}