Error: Class name must be a valid object or a string in Drupal\Core\TypedData\TypedDataManager->createInstance()

Problem/Motivation

I've received this error on installation in two sites.

Error: Class name must be a valid object or a string in Drupal\Core\TypedData\TypedDataManager->createInstance() (line 99 of httpdocs/core/lib/Drupal/Core/TypedData/TypedDataManager.php).

Steps to reproduce

Use composer to add the module and then Install it in Extend > Install New Module.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes