SANS GUI crashes if process with invalid settings

[gemmaguest]

Describe the bug If you attempt to process runs in the ISIS SANS GUI when there are invalid settings, it crashes Mantid.

To Reproduce

• Open the ISIS SANS GUI
• Load the user file MaskFile.toml from the loqdemo in TrainingCourseData (or MaskFile.txt if using v6.3.0 or earlier)
• Load the batch_mode_reduction.csv batch file
• Click the Settings section on the left, and in the Slices box, enter some invalid text, e.g. a space
• Click back on the Runs section on the left. You will get a warning about invalid settings. Click OK.
• On the runs table, click Process All. Mantid crashes.

Expected behavior You should either get another error message, or processing runs should be disabled (with an obvious reason why). Mantid should not crash.

Platform/Version (please complete the following information):

• OS: All
• OS Version:
• Mantid Version: Reproduced in nightly on Ubuntu 20.04. I encountered a hang rather than crash on Windows v6.0.0.

[stale[bot]]

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[stale[bot]]

This issue has been closed automatically. If this still affects you please re-open this issue with a comment or contact us so we can look into resolving it.