Block with non-BigNumber `number` field makes distinctValues throw

[axelchalon]

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eth_newHeads (I think) returns a Block with the number field being a string (e.g. "0x..."); distinctValues assumes that the number field is a BigNumber: https://github.com/paritytech/js-libs/blob/master/packages/light.js/src/utils/operators/distinctValues.ts#L26 and as such we get x.number.eq is not a function