Resolved Import into J2Commerce fails

RO CSVI 9.10.0 — J2Commerce 6 product import crashes on category_path (json_decode null)

Product: RO CSVI 9.10.0 Joomla: 6.1.2 J2Commerce: 6 (latest) PHP: 8.x (deprecation for json_decode(null) is emitted)

Summary

Importing J2Commerce Products with the category_path field populated fails with a 500 / “An error has occurred during the import.” Zero records are processed (Processed: 0) — it dies on the first product while creating/looking up its category, before any product is saved.

Exact error (with Joomla Error Reporting = Maximum)

Deprecated: json_decode(): Passing null to parameter #1 ($json) of type string is deprecated in
/home/<user>/public_html/rvp/plugins/csviaddon/categories/com_categories/model/import/category.php on line 526
With Error Reporting = None the deprecation is suppressed but the import still 500s and still processes 0 records — so this is not merely a cosmetic deprecation notice; json_decode(null) at line 526 cascades into a fatal that halts the import.

Steps to reproduce

Fresh Joomla 6 + J2Commerce 6 + RO CSVI 9.10.0.
Maintenance → update available fields for com_j2commerce (68 fields added).
Create Import template: Action=Import, Component=J2Commerce, Operation=Product, “Use file for configuration”=Yes.
Import a CSV whose header includes category_path (name-path form, e.g. Parent/Child, multiple joined by |).
Preview reads the file correctly (delimiter/enclosure auto-detected, all columns map).
Start import → 500 error, Processed: 0.
Isolation

Removing the category_path column from the CSV is being tested as a workaround; product import without categories is expected to succeed, which further localizes the fault to com_categories/model/import/category.php around line 526.
All other fields verified present on the product table via Available Fields: title, sku, price, main_image, additional_images, introtext, quantity.
Ask

Please confirm whether line 526 of category.php should guard against a null value before json_decode() (e.g. category params/metadata being null for a to-be-created category), and advise on a patch or the correct way to import products with multi-category category_path on J2Commerce 6.