You should take out insurance on credit, ie coverage which guarantees that your bank will be repaid even in the event of death « décès », disability « invalidité » (if you can no longer work after an accident or illness). In some cases they can also offer unemployment insurance / loss of employment « assurance chômage », « assurance perte d'emploi ». Be sure to check the conditions of this guarantee, there is often a delay of several months before being affected by this guarantee (in many cases the first 6 months of unemployment are not compensated for example).
If you buy as a couple you can choose the percentage to cover each depending on your situation (so you can ensure each of you 50% or choose 70 / 30 %...).
You can also choose as the credit guarantee the mortgage on the house. This means that the guarantee is the house itself, if you can
not pay, the bank gets the house.
When you receive your loan offer, costs related to the mortgage must be indicated. If your bank does not give you this cost, consult your notary, the mortgage is a notarial deed « acte notarié » and your notary can tell you what are the costs.