[Bug] `DrawingView` crashes if `Points` and/or `DrawingFinishedCommand` property is not set

[jfversluis]

Description

I tried to implement a simple DrawingView, but it crashed. Looking at the source I need to set both the Points and the DrawingFinishedCommand else it won't work.

Steps to Reproduce

1. Implement DrawingView like below

<xct:DrawingView  BackgroundColor="LightGray" HeightRequest="200"  />

2. Run app
3. Try to draw, the app will crash when you take your finger/pointer of the canvas

Expected Behavior

Line gets drawn

Actual Behavior

NRE and application crashes

Basic Information

• Version with issue: Current nightly
• Last known good version: N/A
• IDE: VSMac
• Platform Target Frameworks:
  • iOS: 14.5
  • Android: Not test, but pretty sure it happens on Android as well
• Android Support Library Version: N/A

Workaround

Assign values to Points and DrawingFinishedCommand

Reproduction imagery

DrawViewCrash1.mov

Reproduction Link

[jfversluis]

@VladislavAntonyuk FYI

[jfversluis]

Fixed in #1459