Fix operator code

Closes #3515141

src/Plugin/GraphQL/EntityQueryBase.php

@@ -228,6 +228,9 @@ class EntityQueryBase extends DataProducerPluginBase implements ContainerFactory
       $operator = !empty($condition['operator']) ? $condition['operator'] : NULL;
       $language = !empty($condition['language']) ? $condition['language'] : NULL;
 
+      // Map GraphQL operator to proper ConditionInterface operator.
+      $operator = static::OPERATOR_MAPPING[$operator] ?? NULL;
+
       // We need at least a value or an operator.
       if (empty($operator) && empty($value)) {
         throw new UserError(sprintf("Missing value and operator in filter for '%s'.", $field));
@@ -261,11 +264,6 @@ class EntityQueryBase extends DataProducerPluginBase implements ContainerFactory
         $operator = is_array($value) ? 'IN' : '=';
       }
 
-      // Map GraphQL operator to proper ConditionInterface operator.
-      if (isset(static::OPERATOR_MAPPING[$operator])) {
-        $operator = static::OPERATOR_MAPPING[$operator];
-      }
-
       // Add the condition for the current field.
       $group->condition($field, $value, $operator, $language);
     }