Mantid crash in Symmetrise tab

[warunawickramasingha]

Describe the bug Mantid crashes when preview button is pressed after clearing ADS in the Inelastic Symmetrise tab

To Reproduce Follow Instruction for Symmetrise Tab

1. Data is loaded at step 4
2. ADS is cleared
3. Preview button is pressed

Expected behavior No Crash

Screenshots

Platform/Version (please complete the following information):

• OS: macOS and IDAaaS.
• Mantid Version 6.11 manual testing

Additional context

[github-actions[bot]]

Closed by #38051.