clients/viem: use interval for routine fetching, unref intervalId

[CedarMist]

Provide actual fix for problem inside #379

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[CedarMist]

This won't work in browsers.

We can do something like:

if( typeof x === 'object' && 'unref' in x && typeof x.unref == 'function' )

or just

if( typeof x.unref === 'function' )

?

Likewise we're not doing any in-browser testing for packages which will primarily be used in browsers, so none of this would've been caught in CI.

[CedarMist]

Will find a way of linting the TS code for NodeJS vs WebBrowser compatibility.

[CedarMist]

Have logged a ticket/discussion with Viem w.r.t async serializers, which would entirely avoid this hacky workaround. I should've done this earlier.

wevm/viem#2696

[aefhm]

A standalone NodeJS script reproduces the exit error pretty easily, but reproducing it in vitest has been tricky. Test harness is not waiting for the Node process, and does not hang which is the behavior we want to reproduce in the failing case. We could use a test script and assert that this exits within 1000 milliseconds though.

const transport = sapphireHttpTransport();
const chain = sapphireLocalnet;
const publicClient = createPublicClient({ chain, transport });
defineChain({
    id: 0x5afd,
    name: "Oasis Sapphire Localnet",
    network: "sapphire-localnet",
    nativeCurrency: { name: "Sapphire Local Rose", symbol: "TEST", decimals: 18 },
    rpcUrls: {
        default: {
            http: ["http://localhost:8545"],
        },
    },
    serializers: {
        transaction: createSapphireSerializer(publicClient)
    },
    testnet: true,
});

[CedarMist]

Ok, I can reproduce this.
It appears that my unref fix works correctly. I will see about how to add a test.

Have added a timeout test, to verify that your example script exits after 2 seconds.