[BUGFIX] Add missing value for area divider item

[HimanshuRamavat07]

Summary

• Fix malformed TCA item in price_measure_unit for backend variants.
• Add missing 'value' => '--div--' to the measure.area divider entry.
• Prevent backend save warning (Undefined array key "value") in TYPO3 DataHandler.

Problem

In Configuration/TCA/tx_cartproducts_domain_model_product_bevariant.php, the item
tx_cartproducts_domain_model_product_product.measure.area is defined without a value.
TYPO3 expects items entries to contain a value and can trigger:
PHP Warning: Undefined array key "value" during save.

Change

Updated:

['label' => $_LLL . ':tx_cartproducts_domain_model_product_product.measure.area', 'value' => '--div--'],

References

• Related issue: Missing value in TCA/tx_cartproducts_domain_model_product_bevariant.php #282