[incoming] Tooltip "Warning: no results" when there are no results

[D-Groenewegen]

Something appears to have changed by SRF v5. If a query has no results and format=incoming is used, I would not expect it to output anything, as I believe was still the case in SRF v4.2.1. By 5.0.0, the result is instead an orange icon with a tooltip saying 'Warning. No results'. I've had no luck trying to suppress the tooltip with default= (no value).

{{#ask: [[MyPage]]
|format=incoming
|default=
}}

The orange icon is not very helpful and in fact, runs up against the same objections that we addressed in #614. I would suggest removing this line of code from SRF_Incoming.php

$result->addErrors( [ wfMessage( 'smw_result_noresults' )->inContentLanguage()->text() ] );