Tabindex works in an unwanted behaviour

[sp90]

Describe the bug
When trying to use tabindex and set on the component like this:

<ng-select tabindex="1"></ng-select>

Then the tabindex is set both on the input field and the component which makes it show when you tab

Reproducbile example
Example which reproduces described behaviour

To Reproduce
Steps to reproduce the behavior (if example is not provided):

1. Click on the stackblitz example
2. Try to tab (then it focuses the wrapper) *ERROR
3. Tab again to target the input

Expected behavior
It should only focus the input

Screenshots

Desktop (please complete the following information):

• OS: MacOS
• Browser: Chrome
• Version 74.0.3729.131

Smartphone (please complete the following information):
Not tested on a smart phone (can you tab on a smart phone)

Additional context
You might resolve this by renaming the tabindex input on the parent to tabIndex.

A hack until this is resolved is to use this:

<ng-select tabindex="1" [attr.tabindex]="-1"></ng-select>

This sets the tabindex on the child and then overwrites the components tabindex on init with the -1