-Existing Parameter name changes to the default name while creating a new parameter.
-The parameter name is also changed to default name on deleting the parameter.
-To delete the parameter need to perform delete action twice on the same parameter.
-IndexOutOfRangeException error is thrown on renaming parameter in Animator controller.

Steps to repro:
1. Create a new Project.
2. Assets > Create > Animation Controller.
3. Click on Parameter Tab > Click on "+" > Float / Int / Bool / Trigger.
4. Rename the Parameter.

Actual Result:
IndexOutOfRangeException errors are thrown in the console.

Expected Result:
No errors in the console.

Reproducible in:
2020.1.0a23, 2020.1.0a22.

Working Fine in:
2020.1.0a21, 2019.3.0f6 (27ab2135bccf).

Note: Find the attached stack trace

Environment:
Occurring on Windows 10 & Mac 10.15.