"InvalidArgumentException: The timestamp must be numeric." error

Problem/Motivation

On a decoupled site where only admins log in, we started seeing these error messages that completely stopped all site functionality once logged in:

InvalidArgumentException: The timestamp must be numeric. in Drupal\Component\Datetime\DateTimePlus::createFromTimestamp() (line 201 of docroot/core/lib/Drupal/Component/Datetime/DateTimePlus.php).

A portion of the backtrace is as follows:

#0 docroot/core/lib/Drupal/Core/Datetime/DateFormatter.php(122): Drupal\Component\Datetime\DateTimePlus::createFromTimestamp(NULL, Object(DateTimeZone), Array)
#1 docroot/modules/contrib/build_hooks/src/DeploymentStorageHandler.php(84): Drupal\Core\Datetime\DateFormatter->format(NULL)
#2 docroot/modules/contrib/build_hooks/src/DeploymentStorageHandler.php(50): Drupal\build_hooks\DeploymentStorageHandler->getLabelForNextDeploymentForEnvironment(Object(Drupal\build_hooks\Entity\FrontendEnvironment))
#3 docroot/modules/contrib/build_hooks/src/DeployLogger.php(90): Drupal\build_hooks\DeploymentStorageHandler->getOrCreateNextDeploymentForEnvironment(Object(Drupal\build_hooks\Entity\FrontendEnvironment))
#4 docroot/modules/contrib/build_hooks/src/DeployLogger.php(108): Drupal\build_hooks\DeployLogger->logEntityCreated(Object(Drupal\file\Entity\File))
#5 docroot/modules/contrib/build_hooks/build_hooks.module(44): Drupal\build_hooks\DeployLogger->logEntityUpdated(Object(Drupal\file\Entity\File))
#6 [internal function]: build_hooks_entity_update(Object(Drupal\file\Entity\File))

Steps to reproduce

TBD, not entirely sure what's triggering the problem.

Proposed resolution

Fix the bug =)

Remaining tasks

Identify the source of the bug.
Fix the bug.

User interface changes

TBD

API changes

TBD

Data model changes

TBD