Error Handling

Every module in viem exports an accompanying error type which you can use to strongly type your catch statements.

These types come in the form of <Module>ErrorType. For example, the getBlockNumber action exports a GetBlockNumberErrorType type.

Unfortunately, TypeScript doesn't have an abstraction for typed exceptions, so the most pragmatic & vanilla approach would be to explicitly cast error types in the catch statement.

example.tsclient.ts

import { type GetBlockNumberErrorType } from 'viem'
import { publicClient } from './client'

try {
  const blockNumber = await client.getBlockNumber()
} catch (e) {
  const error = e as GetBlockNumberErrorType
  error.name
  //    ^? (property) name: "Error" | "ChainDisconnectedError" | "HttpRequestError" | "InternalRpcError" | "InvalidInputRpcError" | "InvalidParamsRpcError" | "InvalidRequestRpcError" | "JsonRpcVersionUnsupportedError" | ... 16 more ... | "WebSocketRequestError"

  if (error.name === 'InternalRpcError')
    error.code
    //    ^? (property) code: -32603

  if (error.name === 'HttpRequestError')
    error.headers
    //    ^? (property) headers: Headers
    error.status
    //    ^? (property) status: number
}

import { type GetBlockNumberErrorType } from 'viem'
import { publicClient } from './client'

try {
  const blockNumber = await client.getBlockNumber()
} catch (e) {
  const error = e as GetBlockNumberErrorType
  error.name
  //    ^? (property) name: "Error" | "ChainDisconnectedError" | "HttpRequestError" | "InternalRpcError" | "InvalidInputRpcError" | "InvalidParamsRpcError" | "InvalidRequestRpcError" | "JsonRpcVersionUnsupportedError" | ... 16 more ... | "WebSocketRequestError"

  if (error.name === 'InternalRpcError')
    error.code
    //    ^? (property) code: -32603

  if (error.name === 'HttpRequestError')
    error.headers
    //    ^? (property) headers: Headers
    error.status
    //    ^? (property) status: number
}

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})

Error Handling ​

Error Handling