[SENTRY] toPairSlug handle undefined token addresses with RPC issues to avoid crashing app

[tiagofilipenunes]

When there are RPC issues and the pairs information cannot be fetched, an error is being thrown from ExplorerHeader -> toPairSlug when getting the base and quote token addresses: Cannot read properties of undefined (reading 'address')

Suggestion: Check if either address is undefined and return an empty pair slug so the user can get the RPC error instead of an app crash error.

URL that is failing: https://sei.carbondefi.xyz/explore/token-pair/0x059a6b0ba116c63191182a0956cf697d0d2213ec_0x3894085ef7ff0f0aedf52e2a2704928d1ec074f1

1. Open the URL above in private browser
2. App crashes with error similar to e is undefined.