Prevent exception when option text converts to false

The function would incorrectly through an exception when the option text was
set to a string that would evaluate to false such as "0"

Fixes #13083

Author: pmclain

app/code/Magento/Eav/Model/Entity/Attribute/OptionManagement.php

@@ -132,7 +132,7 @@ public function getItems($entityType, $attributeCode)
      */
     protected function validateOption($attribute, $optionId)
     {
-        if (!$attribute->getSource()->getOptionText($optionId)) {
+        if ($attribute->getSource()->getOptionText($optionId) === false) {
             throw new NoSuchEntityException(
                 __('Attribute %1 does not contain option with Id %2', $attribute->getAttributeCode(), $optionId)
             );