Function syncMessages

syncMessages(): Promise<void>
Fetch and persist messages from Pinpoint campaigns. Calling this API is necessary to trigger InApp messages on the device.

Returns Promise<void>
A promise that will resolve when the operation is complete.
Throws
service exceptions - Thrown when the underlying Pinpoint service returns an error.

Throws
validation: InAppMessagingValidationErrorCode - Thrown when the provided parameters or library configuration is incorrect, or if In App messaging hasn't been initialized.

Example
```
// Sync InApp messages with Pinpoint and device.
await syncMessages();
```