Error when importing new customers

[duc-tv]

nopCommerce version: 4.7 (latest from develop)

Steps to reproduce the problem:
I am unable to import a new customer list from an Excel file in the case of a new customer list.

Please check this code snippet

If it's a new customer, lastPassword will be null at line 1945, which is the cause of the issue. Perhaps we need to check for null or verify if it's a new customer.

[skoshelev]

Closed #7181