Allow only Layer1 / Layer2 to be passed in for `fromEthersProvider`

Currently Resolution.fromEthersProvider can only be used with two types of params:

Resolution.fromEthersProvider({}) (because the networks {} is not optional)

Resolution.fromEthersProvider({uns: {
    locations: {
      Layer1: {
        network: 'mainnet',
        provider: mainnetProvider
      },
      Layer2: {
        network: 'polygon-mainnet',
        provider: polygonProvider
      }
    }
}});

I'd like to only resolve UD in Layer1, but not passing Layer2 would throw the following error:

Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'network')
    at Resolution.fromEthersProvider (Resolution.js:320:1)
    at tryLookupUDName (HeaderAccountPopover.tsx:64:1)
    at resolveENSInfo (HeaderAccountPopover.tsx:118:1)
    at HeaderAccountPopover.tsx:128:1
    at invokePassiveEffectCreate (react-dom.development.js:23487:1)
    at HTMLUnknownElement.callCallback (react-dom.development.js:3945:1)
    at Object.invokeGuardedCallbackDev (react-dom.development.js:3994:1)
    at invokeGuardedCallback (react-dom.development.js:4056:1)
    at flushPassiveEffectsImpl (react-dom.development.js:23574:1)
    at unstable_runWithPriority (scheduler.development.js:468:1)
    at runWithPriority$1 (react-dom.development.js:11276:1)
    at flushPassiveEffects (react-dom.development.js:23447:1)
    at react-dom.development.js:23324:1
    at workLoop (scheduler.development.js:417:1)
    at flushWork (scheduler.development.js:390:1)
    at MessagePort.performWorkUntilDeadline (scheduler.development.js:157:1)

Could you please allow only passing in one location?

Reference

https://github.com/unstoppabledomains/resolution/blob/62dd1ccfc58fc192a6432269c046042b295d622d/src/Resolution.ts#L387-L421

unstoppabledomains / resolution

Allow only Layer1 / Layer2 to be passed in for `fromEthersProvider` #229

Reference