[BUG] searchFieldDrop's index might be null

[mpf82]

searchFieldDrop's index might be null if searching for a field that is not part of the grid (which in our application is a common usecase, to filter based on database fields that are not displayed in the grid).

In that case, this.getSearch(sd.field, true) returns null and as a result, the HTML of the search action contains searchFieldDrop|null|0|this.

If you now click on such a search action, the following error will be raised:

w2ui.js:4291 Uncaught TypeError: Cannot read properties of undefined (reading 'type')
    at w2grid.searchFieldDrop (w2ui.js:4291)
    at HTMLSpanElement.<anonymous> (w2ui.js:1943)
    at HTMLSpanElement.dispatch (jquery-3.6.0.js:5430)
    at HTMLSpanElement.elemData.handle (jquery-3.6.0.js:5234)

Using sd_ind (and searchData) in such a case will probably not work, because the search data is unlikely to contain a type property.

Maybe text should be assumed as fallback type in such a case? And searchData[sd_ind].field / searchData[sd_ind].operator could be used as fallback for sf.field / sf.operators.

[vitmalina]

This has been refactored in the past few weeks and I think it is working fine now. However, can you check and close this issue if all good?