Steps to Reproduce:
1. Configure Payment Term (Accounting > Configuration > Payment Terms) containing multiple installments.
2. Create a Customer Invoice with this Payment Term.
3. Post the invoice.
4. Register a payment and fully reconcile one of the installments.
5. Navigate to the customer's Follow-Up Report (Accounting > Reporting > Partner Ledger > Report: Follow-Up Report).
6. Navigate to remaining open installment/account move line for that invoice.
7. Turn On or Off the No Follow-Up toggle for the invoice.

An error occurs when enabling or disabling the No Follow-Up toggle.

Issue:
Enabling or disabling the No Follow-Up toggle on a remaining open installment in the Follow-Up Report raises a server error when the invoice contains multiple installments and one or more installments are already fully reconciled.

Root Cause:
The Follow-Up Report only loads and sends non-fully reconciled account move lines from the JavaScript side through all_line_ids. In action_toggle_no_followup(), when the selected line belongs to an invoice, the code retrieves all receivable/payable lines of the invoice, including fully reconciled installments:

```
move.line_ids.filtered(
    lambda line: line.account_type in ('asset_receivable', 'liability_payable'),
)
```

The method then attempts to map every receivable/payable line to a report line ID using aml_id_to_line_id. Since fully reconciled installments are not present in all_line_ids, they are missing from the mapping dictionary, causing a KeyError when accessing:

`aml_id_to_line_id[line.id]
`

Fix:
Restricted the impacted lines to those present in the report by adding a check that the account move line exists in aml_id_to_line_id before performing the mapping:

```
lambda line: line.account_type in ('asset_receivable', 'liability_payable')
             and line.id in aml_id_to_line_id
```


opw-6245448

Forward-Port-Of: odoo/enterprise#126156