Translate two missing sentences in the article 'promise-error-handling'

[NitiemaAllassane]

This pull request completes the French translation of the article promise-error-handling by translating two missing sentences that were still in English.

Sentence 1: In the example below the .catch successfully handles the error: Dans l’exemple ci-dessous, le .catch gère correctement l’erreur.

Sentence 2: The execution jumps from the first .catch () to the next one (**) down the chain. L’exécution passe du premier .catch () au suivant (**) plus bas dans la chaîne.

Linked to issue: #510

[CLAassistant]

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