SQLSTATE[23000] Error when create a Bill in Purchase module

SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'account_id' cannot be null (SQL: insert into `szq_double_entry_ledger` (`company_id`, `account_id`, `ledgerable_id`, `ledgerable_type`, `issued_at`, `entry_type`, `credit`, `updated_at`, `created_at`) values (1, ?, 10, App\Models\Purchase\Bill, 2020-11-12 12:13:27, total, 0, 2020-11-12 12:13:27, 2020-11-12 12:13:27))

This error occured when I create a new bill. Can anyone explain or help me to fix this error?

You should install the Double-Entry app for that company. Feel free to use the ticket system for further app support.

Just in case anyone has a similar issue - I was receiving an SQL duplicate key error message and then stumbled upon this post. The fix was the same - to enable the Double-Entry app for that company.