FIX: Error thrown when Cancelling Control Scheme creation in Input actions Editor (ISXB-892)

[bmalrat]

Description

Fixed error thrown when Cancelling Control Scheme creation in Input actions Editor
ISXB-892

Changes made

Added a check in ControlSchemeCommands::ResetSelectedControlScheme() to ensure that we are not searching for a non existing scheme when deleted.

Checklist

Before review:

• Changelog entry added.
  • Explains the change in Changed, Fixed, Added sections.
  • For API change contains an example snippet and/or migration example.
  • FogBugz ticket attached, example ([case %number%](https://issuetracker.unity3d.com/issues/...)).
  • FogBugz is marked as "Resolved" with next release version correctly set.
• Tests added/changed, if applicable.
  • Functional tests Area_CanDoX, Area_CanDoX_EvenIfYIsTheCase, Area_WhenIDoX_AndYHappens_ThisIsTheResult.
  • Performance tests.
  • Integration tests.
• Docs for new/changed API's.
  • Xmldoc cross references are set correctly.
  • Added explanation how the API works.
  • Usage code examples added.
  • The manual is updated, if needed.

During merge:

• Commit message for squash-merge is prefixed with one of the list:
  • NEW: ___.
  • FIX: ___.
  • DOCS: ___.
  • CHANGE: ___.
  • RELEASE: 1.1.0-preview.3.

[ekcoh]

LGTM

[Pauliusd01]

LGTM, checked adding new control schemes, editing them, and cancelling those changes at various times.

[Pauliusd01]

Reran failed tests, will merge/verify bug on Jira once those pass