Synchronous errors thrown by async methods

Handle synchronous errors thrown by asynchronous methods in the Instant Games SDK.

To handle asynchronous errors only, refer to Asynchronous errors.

Async methods throwing JsException and APIError

Asynchronous methods can throw synchronous exceptions, which occur when the method is called, and asynchronous exceptions, which occur when the returned task is awaited.

For example, the endpoint FBInstant.Player.SetDataAsync throws JsException synchronously if the string provided isn't valid JSON:

// throws JsException:
var task = FBInstant.Player.SetDataAsync("{ invalid JSON }");

But it can also throw APIError asynchronously for a variety of reasons, for example, if a previous call to the endpoint hasn't yet completed:

// doesn't throw:
var task = FBInstant.Player.SetDataAsync("{ \"myKey\": \"my value\" }");

// throws APIError with ErrorCode.PENDING_REQUEST:
await task;

Error handling

To handle both synchronous and asynchronous errors, you can do either of the following:

  • Use separate try blocks for the two phases of execution (calling the function, then awaiting the task).

  • Combine the two phases in a single expression that both calls the function and awaits the result, using a single try block and multiple catch blocks:

    try
{
    await FBInstant.Player.SetDataAsync(someString);
}
catch (APIError e)
{
    // handle the various kinds of APIError the endpoint might throw
}
catch (JsException e)
{
    // handle invalid JSON
}
    Note

    In this example, the catch block for APIError must precede that for JsException because APIError derives from JsException.

Additional resources