Implemented Viem in our codebase but struggling a lot with typescript

[NBMSacha]

GM!

We're been implementing viem to Mobula's front-end & we add many hacky stuff to do to get it compile with typescript, here's an example:

 const publicClient = createPublicClient({
            chain: idToWagmiChain[blockchain.chainId],
            transport: http(blockchain.rpcs[0]),
          });

 const contract = getContract({
            address: search as `0x${string}`,
            abi: erc20ABI,
            publicClient: publicClient as never,
}) as any;

const symbol = await contract.read.symbol();

If we don't add "as never" and "as any", we get:

Type '{ account: undefined; batch?: { multicall?: boolean | { batchSize?: number; wait?: number; }; }; cacheTime: number; chain: Chain; key: string; name: string; pollingInterval: number; request: EIP1193RequestFn<PublicRpcSchema>; ... 49 more ...; extend: <const client extends { ...; }>(fn: (client: Client<...>) => clien...' is not assignable to type 'never'.
  The intersection 'Client<Transport, Chain>' was reduced to 'never' because property 'cacheTime' has conflicting types in some constituents.t

And

Property 'read' does not exist on type 'never'.t

Which might be the same issue.

Any idea what we did wrong?

[tmm]

Do you have TypeScript strict mode on? Can you share a complete example for what you are running into?

[metabacalhau]

Hi @tmm, here is the code that gives me the error:

import { Chain, createPublicClient, getContract, http } from 'viem'

export async function getWeb3ViemClients() {
  const publicClient = createPublicClient({
    chain: {} as Chain,
    transport: http(),
  })

  getContract({
    address: '0x0000000000000000000000000000000000000000',
    client: {
      public: publicClient,
    },
  })
}

The error happens at line public: publicClient,:
Type '{ account: undefined; batch?: { multicall?: boolean | { batchSize?: number; wait?: number; }; }; cacheTime: number; chain: Chain; key: string; name: string; pollingInterval: number; request: EIP1193RequestFn<PublicRpcSchema>; ... 50 more ...; extend: <const client extends { ...; } & ExactPartial<...>>(fn: (client: C...' is not assignable to type 'never'. The intersection 'Client<Transport, Chain>' was reduced to 'never' because property 'cacheTime' has conflicting types in some constituents.

TypeScript: 5.4.2
Viem: 2.8.13

Could you please tell us how to fix this issue?

[tmm]

Works fine for me: TypeScript Playground

[tungkiet7]

@tmm Could you please tell us how to fix this issue?

[DLHTX]

I have the same problem. You can check whether the tsconfig file has StructNullChecks, and if not,just add "StructNullChecks": true.

[SanyaSemenov]

@NBMSacha please tell that you managed to handle it 😅 please provide your solution if you have one

[NBMSacha]

Yes, I was a typescript newbie at the time, that's why. The way to fix this is so use "as const" on your ABIs & most stuff.

[SanyaSemenov]

Nah, I wish the issue was about it, but I tend to think that it's packages versions mismatch because even if I copypaste pancakeswap's getContract helper (I'm making smth similar), the issue is the same (about 'cacheTime')