I apologize if the answer to this is obvious, but I am newly-embarked on porting a number of complex custom Drupal 7 modules to Drupal 9. I am using Drupal version 9.3.6, PHP version 7.4.28, mysql, apache2. I have created a custom field as follows, which on install goes without errors and appears in the field list report:

langcode: en status: true dependencies:   module:     - user   enforced:     module:       - test_module id: user.field_test field_name: field_test entity_type: user type: string_long settings:   case_sensitive: false module: core locked: false cardinality: 1 translatable: true indexes: {  } persist_with_no_fields: false custom_storage: false 

But when I try to instantiate it, either with field.field.user.user.field_test.yml or manually through the UI, I get the following error stack:

 [warning] A non-numeric value encountered TypedConfigManager.php:189  [error]  Error: Unsupported operand types in DrupalCoreConfigTypedConfigManager->getDefinitionWithReplacements() (line 189 of /var/www/test_site/web/core/lib/Drupal/Core/Config/TypedConfigManager.php) #0 /var/www/test_site/web/core/lib/Drupal/Core/Config/TypedConfigManager.php(105): DrupalCoreConfigTypedConfigManager->getDefinitionWithReplacements() 

(Sorry, I had to delete the remainder of the stack dump to avoid getting flagged as spam!)

This is the part of TypedConfigManager as follows:

    // Add type and default definition class.     $definition += [       'definition_class' => 'DrupalCoreTypedDataDataDefinition', // Here is line 189       'type' => $type,       'unwrap_for_canonical_representation' => TRUE,     ];     return $definition; 

I am at a loss here. If I create the field storage through the admin interface and instantiate also through the admin interface, everything works fine. I export those definitions through the single export interface, and then I get the failure.

Thank you in advance for any insight!