Cannot Generate GSTR-2 Report "Server Error"

Locally hosted ERPNext.
ERPNext: v12.31.0 (version-12)
Frappe Framework: v12.28.0 (version-12)

When I’m trying to generate GSTR-2 report, I get the following error:
TypeError: unsupported operand type(s) for +: ‘int’ and ‘str’