User still able to register with non-existent BPNL

[JordanGerada3]

Current Behaviour

When a user inputs an invalid BPNL in the autofill field, the input displays an error "This BPN doesn't exist, please enter a valid BPN or use the manual flow below." However, the invalid BPNL populates the BPN field in the form, allowing the user to submit the registration with an incorrect BPN.

Expected Behaviour

An invalid BPNL inserted into the input field shows an error and is not displayed in the BPN field of the form.

Steps To Reproduce

• Login to the application as CX-admin/operator
• Invite Business partner
• Accept invite as an invited user
• Start the registration process
• Add any dummy BPN in the BPNL field e.g: BPNL0000000009Z0
• Ignore error and add company data in rest of the fields like address, VAT ID etc
• Continue and proceed with further steps of registration
• Submit the registration

[typecastcloud]

Resolved via #253