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.

import { type 
type GetBlockNumberErrorType = RequestErrorType
GetBlockNumberErrorType } from 'viem'
import { 
const client: {
  account: undefined;
  batch?: {
    multicall?: boolean | {
      batchSize?: number | undefined;
      wait?: number | undefined;
    } | undefined;
  } | undefined;
  cacheTime: number;
  chain: {
    blockExplorers: {
      ...;
    };
    ... 9 more ...;
    fees?: ChainFees<...> | undefined;
  };
  ... 53 more ...;
  extend: <const client extends {
    ...;
  } & Partial<...>>(fn: (client: Client<...>) => client) => Client<...>;
}
client } from './client'
 
try {
  const 
const blockNumber: bigint
blockNumber = await 
const client: {
  account: undefined;
  batch?: {
    multicall?: boolean | {
      batchSize?: number | undefined;
      wait?: number | undefined;
    } | undefined;
  } | undefined;
  cacheTime: number;
  chain: {
    blockExplorers: {
      ...;
    };
    ... 9 more ...;
    fees?: ChainFees<...> | undefined;
  };
  ... 53 more ...;
  extend: <const client extends {
    ...;
  } & Partial<...>>(fn: (client: Client<...>) => client) => Client<...>;
}
client.
getBlockNumber: (args?: GetBlockNumberParameters | undefined) => Promise<bigint>Returns the number of the most recent block seen.
Docs: https://viem.sh/docs/actions/public/getBlockNumber
Examples: https://stackblitz.com/github/wevm/viem/tree/main/examples/blocks/fetching-blocks
JSON-RPC Methods: eth_blockNumber
getBlockNumber()
} catch (
var e: unknown
e) {
  const 
const error: GetBlockNumberErrorType
error = 
var e: unknown
e as 
type GetBlockNumberErrorType = RequestErrorType
GetBlockNumberErrorType
  
const error: GetBlockNumberErrorType
error.
name: "Error" | "ChainDisconnectedError" | "HttpRequestError" | "InternalRpcError" | "InvalidInputRpcError" | "InvalidParamsRpcError" | "InvalidRequestRpcError" | "JsonRpcVersionUnsupportedError" | ... 16 more ... | "WebSocketRequestError"name 
 
 
 
 
 
 
  if (
const error: GetBlockNumberErrorType
error.
name: "Error" | "ChainDisconnectedError" | "HttpRequestError" | "InternalRpcError" | "InvalidInputRpcError" | "InvalidParamsRpcError" | "InvalidRequestRpcError" | "JsonRpcVersionUnsupportedError" | ... 16 more ... | "WebSocketRequestError"
name === 'InternalRpcError')
    
const error: InternalRpcErrorType
error.
code: -32603code
 
 
  if (
const error: GetBlockNumberErrorType
error.
name: "Error" | "ChainDisconnectedError" | "HttpRequestError" | "InternalRpcError" | "InvalidInputRpcError" | "InvalidParamsRpcError" | "InvalidRequestRpcError" | "JsonRpcVersionUnsupportedError" | ... 16 more ... | "WebSocketRequestError"
name === 'HttpRequestError') {
    
const error: HttpRequestErrorType
error.
HttpRequestError.headers?: Headers | undefinedheaders
 
 
    
const error: HttpRequestErrorType
error.
HttpRequestError.status?: number | undefinedstatus
  }
}