NullReferenceException is thrown on enabling quick search with background task window (show progress details ) which shows the progress the of “building assets search index “. Refer attached video and stack trace.

Steps to repro:
1. Create a new HDRP project
2. While the template is loading, open the background task window
3. Open Quick search window
4. Observe the "Building assets search index" progress bar in the background task window.
5.Observe NullReferenceException throws as soon as the progress bar exceeds 50%.

Actual Result: NullReferenceException is thrown on enabling quick search with background task window in HDRP template.

Expected Result: No error in the console on enabling quick search with background task window

Occurring on: 2021.2.0a4, 2021.1.0b6, 2021.1.0b5
Working Fine: 2021.1.0b4, 2021.1.0a1

Note:
1. "Quick Search" is a Built-In Package in Unity 2021.1.0a1.
2. Error is not thrown if the background task window is not enabled.