Error Callback with try/catch

error.js

// Disclaimer: I am probably pretty wrong about this.

thing.handle( function( err, data ) {
  try {
    if ( err ) throw err
  // js doesn't support specific errors like this, you can only catch a generic error...
  } catch( NoNetworkConnection e ) {
    window.alert( 'check your internet connection' )
  } catch( InvalidPassword err ) {
    window.alert( 'check your password' )
  }
})