Layer’s React components expose error callbacks to notify you of errors that occur within the embedded components. Use the onError property on <LayerProvider> to get notified about all exceptions within the components: 
<LayerProvider
  businessId="..."
  environment="..."
  appId="..."
  onError={err => console.log('My error callback', err)}
>
  {...}
</LayerProvider>
This can be done both on the top level <LayerProvider> component and within specific components. 
<BankTransactions onError={e => console.log('My callback:', e)} />