Delete text from RichTextArea in WPF

[onepiecefreak3]

Expected Behavior

When using RichTextArea.Buffer.Delete(new Range<int>(0,3)) I expect the first 3 characters in the RichTextArea to be deleted from its buffer.

Actual Behavior

No matter the validity of the range, the method throws an ArgumentNullException when the PresentationFramework seems to evaluate the inner _textData to set.

Steps to Reproduce the Problem

1. Create a RichTextArea.
2. Fill it with text.
3. Try to delete a valid range of it by the Delete method on its Buffer.

Specifications

• Version: 2.5.11, latest develop version
• Platform(s): WPF (could be an issue on other platforms)
• Operating System(s): Windows 10 64bit

Fix

PR #2006 fixes this issue by setting the Text property of the text range retrieved by the control handler to string.Empty instead of null. After some tests, this exudes the expected behaviour and doesn't seem to cause any side effects on the remaining text, regarding formatting or selection.