Prerequisites

• I have read the Contributing Guidelines.
• I agree to follow the Code of Conduct.
• I have searched for existing issues that already report this problem, without success.

Ionic Framework Version

• v4.x
• v5.x
• v6.x
• Nightly

Current Behavior

It is not possible to write conditional fill on ion-button with undefined.

on first load

click on any tab

Expected Behavior

It should have the same first load button color as we are assigning undefined;

Or

Introduce new value called fill='none'

Steps to Reproduce

repo: https://github.com/indraraj26/storage-boolean-issue/tree/ion-button-fill

1. git clone https://github.com/indraraj26/storage-boolean-issue/tree/ion-button-fill
2. ionic serve
3. see the first tab
4. click on any tabs

Code Reproduction URL

https://github.com/indraraj26/storage-boolean-issue/tree/ion-button-fill

Ionic Info

Ionic:

Ionic CLI : 6.19.0 (C:\Users\user\AppData\Roaming\npm\node_modules@ionic\cli)
Ionic Framework : @ionic/angular 6.1.3
@angular-devkit/build-angular : 13.2.6
@angular-devkit/schematics : 13.2.6
@angular/cli : 13.2.6
@ionic/angular-toolkit : 6.1.0

Capacitor:

Capacitor CLI : 3.5.0
@capacitor/android : 3.6.0
@capacitor/core : 3.6.0
@capacitor/ios : not installed

Utility:

cordova-res : 0.15.4
native-run : 1.5.0

System:

NodeJS : v14.17.1 (C:\Program Files\nodejs\node.exe)
npm : 6.14.13
OS : Windows 10

Additional Information

No response