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# @solana/programs

This package contains helpers for identifying custom program errors. It can be used standalone, but it is also exported as part of Kit [`@solana/kit`](https://github.com/anza-xyz/kit/tree/main/packages/kit).

## Functions

### `isProgramError()`

This function identifies whether an error -- typically caused by a transaction failure -- is a custom program error from the provided program address. It takes the following parameters:

- The `error` to identify.
- The `transactionMessage` object that failed to execute. Since the RPC response only provides the index of the failed instruction, the transaction message is required to determine its program address.
- The `programAddress` of the program from which the error is expected to have originated.
- Optionally, the expected error `code` of the custom program error. When provided, the function will check that the custom program error code matches the given value.

```ts
try {
    // Send and confirm your transaction.
} catch (error) {
    if (isProgramError(error, transactionMessage, myProgramAddress, 42)) {
        // Handle custom program error 42 from this program.
    } else if (isProgramError(error, transactionMessage, myProgramAddress)) {
        // Handle all other custom program errors from this program.
    } else {
        throw error;
    }
}
```