Fix tests

Author: djhi

packages/ra-ui-materialui/src/field/ArrayField.tsx

@@ -97,9 +97,6 @@ ArrayFieldImpl.displayName = 'ArrayFieldImpl';
 
 export const ArrayField = genericMemo(ArrayFieldImpl);
 
-ArrayField.propTypes = ArrayFieldImpl.propTypes;
-ArrayField.displayName = 'ArrayField';
-
 export interface ArrayFieldProps<
     RecordType extends Record<string, unknown> = Record<string, any>
 > extends FieldProps<RecordType> {

packages/ra-ui-materialui/src/field/genericMemo.ts

@@ -16,6 +16,6 @@ export const genericMemo: <T extends FunctionComponent>(component: T) => T = <
     // On the memoized version so that components that inspect their children props may read them.
     result.propTypes = component.propTypes;
     result.defaultProps = component.defaultProps;
-    result.displayName = component.displayName.replace('Impl', '');
+    result.displayName = component.displayName?.replace('Impl', '');
     return result;
 };