System.NullReferenceException: MaterialLabel with TypeScale

[PaulP92]

Describe the bug
If you use the default Material.Configuration and add a MaterialLabel with TypeScale to a Page a System.NullReferenceException is thrown.

To Reproduce
Steps to reproduce the behavior:

1. Call XF.Material.Forms.Material.Init(this); (without MaterialConfiguration)
2. Add a MaterialLabel to MainPage
3. Set TypeScale to H5
4. See error

Expected behavior
Use MaterialLabel with default system Fonts

Smartphone:

• Device: iPhone XS Max Simulator
• OS: 12.1

Additional context
Stacktrace:
" at XF.Material.Forms.UI.MaterialLabel.OnTypeScaleChanged (XF.Material.Forms.Resources.Typography.MaterialTypeScale materialTypeScale) [0x0005f] in /Users/vsts/agent/2.146.0/work/1/s/XF.Material/XF.Material.Forms/UI/MaterialLabel.cs:94 \n at XF.Material.Forms.UI.MaterialLabel.OnPropertyChanged (System.String propertyName) [0x00014] in /Users/vsts/agent/2.146.0/work/1/s/XF.Material/XF.Material.Forms/UI/MaterialLabel.cs:56 \n at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00114] in D:\\a\\1\\s\\Xamarin.Forms.Core\\BindableObject.cs:622 \n at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0015b] in D:\\a\\1\\s\\Xamarin.Forms.Core\\BindableObject.cs:422 \n at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value, System.Boolean fromStyle, System.Boolean checkAccess) [0x0003d] in D:\\a\\1\\s\\Xamarin.Forms.Core\\BindableObject.cs:572 \n at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value) [0x00000] in D:\\a\\1\\s\\Xamarin.Forms.Core\\BindableObject.cs:122 \n at MaterialUX.MainPage.InitializeComponent () [0x00012]..."

[songurov]

xmlns:mtrl="clr-namespace:XF.Material.Forms.Resources;assembly=XF.Material.Forms"
xmlns:mtrltypo="clr-namespace:XF.Material.Forms.Resources.Typography;assembly=XF.Material.Forms"

<mtrltypo:MaterialFontConfiguration
x:Key="Material.Font"
Body1="{StaticResource FontFamily.RobotoRegular}"
Body2="{StaticResource FontFamily.RobotoRegular}"
Button="{StaticResource FontFamily.RobotoMedium}"
Caption="{StaticResource FontFamily.RobotoRegular}"
H1="{StaticResource FontFamily.RobotoRegular}"
H2="{StaticResource FontFamily.RobotoRegular}"
H3="{StaticResource FontFamily.RobotoRegular}"
H4="{StaticResource FontFamily.RobotoRegular}"
H5="{StaticResource FontFamily.RobotoRegular}"
H6="{StaticResource FontFamily.RobotoMedium}"
Overline="{StaticResource FontFamily.RobotoRegular}"
Subtitle1="{StaticResource FontFamily.RobotoRegular}"
Subtitle2="{StaticResource FontFamily.RobotoMedium}" />
<mtrl:MaterialColorConfiguration
x:Key="Material.Color"
Background="#EAEAEA"
Error="#B00020"
OnBackground="#000000"
OnError="#FFFFFF"
OnPrimary="#FFFFFF"
OnSecondary="#FFFFFF"
OnSurface="#000000"
Primary="#6200EE"
PrimaryVariant="#6200EE"
Secondary="#00377b"
Surface="#FFFFFF" />
<mtrl:MaterialConfiguration
x:Key="Material.Style"
ColorConfiguration="{StaticResource Material.Color}"
FontConfiguration="{StaticResource Material.Font}" />

<x:Double
x:Key="Material.FontSize.H1">96</x:Double>
<x:Double
x:Key="Material.FontSize.H2">60</x:Double>
<x:Double
x:Key="Material.FontSize.H3">48</x:Double>
<x:Double
x:Key="Material.FontSize.H4">34</x:Double>
<x:Double
x:Key="Material.FontSize.H5">24</x:Double>
<x:Double
x:Key="Material.FontSize.H6">20</x:Double>
<x:Double
x:Key="Material.FontSize.Subtitle1">16</x:Double>
<x:Double
x:Key="Material.FontSize.Subtitle2">14</x:Double>
<x:Double
x:Key="Material.FontSize.Body1">16</x:Double>
<x:Double
x:Key="Material.FontSize.Body2">14</x:Double>
<x:Double
x:Key="Material.FontSize.Button">14</x:Double>
<x:Double
x:Key="Material.FontSize.Caption">12</x:Double>
<x:Double
x:Key="Material.FontSize.Overline">10</x:Double>


<x:Double
x:Key="Material.LetterSpacing.H1">-1.5</x:Double>
<x:Double
x:Key="Material.LetterSpacing.H2">-0.5</x:Double>
<x:Double
x:Key="Material.LetterSpacing.H3">0</x:Double>
<x:Double
x:Key="Material.LetterSpacing.H4">0.25</x:Double>
<x:Double
x:Key="Material.LetterSpacing.H5">0</x:Double>
<x:Double
x:Key="Material.LetterSpacing.H6">0.15</x:Double>
<x:Double
x:Key="Material.LetterSpacing.Subtitle1">0.15</x:Double>
<x:Double
x:Key="Material.LetterSpacing.Subtitle2">0.1</x:Double>
<x:Double
x:Key="Material.LetterSpacing.Body1">0.5</x:Double>
<x:Double
x:Key="Material.LetterSpacing.Body2">0.25</x:Double>
<x:Double
x:Key="Material.LetterSpacing.Button">1.25</x:Double>
<x:Double
x:Key="Material.LetterSpacing.Caption">0.4</x:Double>
<x:Double
x:Key="Material.LetterSpacing.Overline">1.5</x:Double>
<x:Double
x:Key="Material.LetterSpacing.None">0</x:Double>


<OnIdiom.Tablet>560</OnIdiom.Tablet>
<OnIdiom.Phone>280</OnIdiom.Phone>

insert in App.xaml Resource and add fonts per/Platform