emit_error
Description:
Emits a fatal error in response to the request.
This completes the request, so no more data or errors can be emitted after this. Non-fatal errors should not be reported.
If [property@DataSourceRequest:data] was previously set, it will be cleared.
Parameters:
| this | 
           a [class@DataSourceRequest]  | 
      
| error | 
           an error  |