[Bug] System.InvalidOperationException: 'Invalid on Color.Default'

## 🐛 Bug Report

I'm using a MaterialButton. The app is crazing in the init with the following code:
```
...
_materialButton.TextColor.MultiplyAlpha(0.38).ToAndroid()
...
```
Link file [here](https://github.com/Baseflow/XF-Material-Library/blob/e70ca0b8aaef0e069743bf92407cfa6ac320bfc2/XF.Material/Platforms/Android/Renderers/MaterialButtonRenderer.cs#L95
). More info [here](https://github.com/xamarin/Xamarin.Forms/issues/14173).

### Reproduction steps
I just add a material button and the app cant compile.

### Configuration

**Version:** 1.7.8

**Platform:**
- [ ] :iphone: iOS
- [x] :robot: Android
- [ ] :checkered_flag: WPF
- [ ] :earth_americas: UWP
- [ ] :apple: MacOS
- [ ] :tv: tvOS
- [x] :monkey: Xamarin.Forms