Currently, an error occurs when a user tries to generate a lot number without 'Quantity per Lot'.

Step to produce:

- Install the `stock` and `purchase` modules.
- Open Purchase / Orders / Requests for Quotation, Create a new record
- Add a vendor and product that is by lot, Click on 'Confirm Order', and after that click on  'Receive Products'
- Click on the Detailed button to open a 'Detailed Operation'.
- Click on `Generate Serials/Lots button` and remove the 'Quantity per Lot' value and add a double white space after that try to generate a lot number

`TypeError: '<=' not supported between instances of 'NoneType' and 'int'`

This happens because the system tries to compare between Nonetype and integer at [1].

Link [1]: https://github.com/odoo/odoo/blob/3c65ffa8aaf76de7d1aec4a85f1b34429d4c74ef/addons/stock/models/stock_move.py#L958

To resolve this issue, Modified the assignment of `count` at [2] to ensure that it is always assigned a valid numeric value instead of NaN or non-numeric.

Link [2]: https://github.com/odoo/odoo/blob/3c65ffa8aaf76de7d1aec4a85f1b34429d4c74ef/addons/stock/static/src/widgets/generate_serial.js#L49-L53

Sentry-6281418981


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