chore(node): [#1999] panic on upnp event `GatewayNotFound`

[mickvandijke]

Description

Makes a node panic on the upnp event GatewayNotFound. This event only fires when the node runs with the --upnp flag and libp2p couldn't find the upnp gateway to open ports on.

Related Issue

Fixes #1999

Type of Change

Please mark the types of changes made in this pull request.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation update
• [x] Other (please describe): Makes it easier to detect a problem with UPnP.

Checklist

Please ensure all of the following tasks have been completed:

• [x] I have read the contributing guidelines.
• [x] I have performed a self-review of my own code.
• [ ] I have commented my code, particularly in hard-to-understand areas.
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [ ] New and existing unit tests pass locally with my changes.
• [ ] I have updated the documentation accordingly.
• [x] I have followed the conventional commits guidelines for commit messages.
• [ ] I have verified my commit messages with commitlint.