Only call .removeAllListeners if it exists

[gamalielhere]

Description

This fixes the issue where MEWWallet exits after connecting

Checklist:

• [x] My code follows the code style of this project.
• [x] My code implements all the required features.

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Name	Status	Preview	Updated
ens-app	✅ Ready (Inspect)	Visit Preview	May 12, 2022 at 2:02AM (UTC)

[makoto]

Thank you for your contribution. I tested and seems working fine