MultiSelect with custom target closes automatically when clearing the search query

[benochr]

Environment

• Package version(s): 5.17.6 (@blueprintjs/core), 5.3.18 (@blueprintjs/select)
• Operating System: macOS Sequoia 15.3.2
• Browser name and version: Chrome 134.0.6998.165

Code Sandbox

https://blueprintjs.com/docs/#select/multi-select

Steps to reproduce

1. Enable "Use Custom Target"
2. Click on the custom target and search on any string
3. Remove the search string with backspace
4. Popover closes when last character is removed

Actual behavior

The popover of the MultiSelect closes automatically when the last character of the search string is removed. The same happens when you select the whole search string and remove it at once. This is annoying if the user want to do multiple searches in sequence.

Expected behavior

The popover remains open when the search string is cleared.

Possible solution

In packages/select/src/components/multi-select/multiSelect.tsx, the logic in handleQueryChange that updates the isOpen state should be changed.