[2.0.10] Property access error in DerivableContextSourceBase->calculateDependencies()

When I call Source::calculateDependencies() from Display Builder I have this error:

Error: Typed property Drupal\ui_patterns\SourcePluginBase::$propDefinition must not be accessed before initialization in Drupal\ui_patterns\SourcePluginBase->getPropDefinition() (line 333 of modules/custom/ui_patterns/src/SourcePluginBase.php. 

Backtrace:

• Drupal\ui_patterns\Plugin\UiPatterns\Source\DerivableContextSourceBase->isSlot() (Line: 159)
• Drupal\ui_patterns\Plugin\UiPatterns\Source\DerivableContextSourceBase->getSourcePlugins() (Line: 561)
• Drupal\ui_patterns\Plugin\UiPatterns\Source\DerivableContextSourceBase->calculateDependencies() (Line: 145)
• Drupal\display_builder\Entity\PatternPreset->calculateDependencies() (Line: 329)