Ticket2023 dae crashing if disconnected

[Tom-Willemsen]

Description of work

Adds a null check against period control type

To test

ISISComputingGroup/IBEX#2023

Acceptance criteria

Unfortunately we haven't found a way to reproduce the crash as reported on the initial ticket. If DAE is not running the instrument just stays in a "processing" state and on a real instrument you'll get a popup saying "DAE not running". After a chat with @FreddieAkeroyd we think it's getting some bad XML from somehow, which causes a value to go to null and then the DAE perspective to crash with a NullPointerException

From the stack trace/code, I've added a null check and a unit test against the appropriate behaviour.

Reviewer, merge this/mark complete if it looks like a sensible solution to the exception in the original ticket. You're welcome to look for ways to reproduce it, but obviously it has already been looked at without success.

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Code Review

• Is the code of an acceptable quality?
• Does the code conform to the coding standards? Is it well structured with small focussed classes/methods/functions?
• Are there unit tests in place? Are the unit tests small and test the a class in isolation?
• Are there automated system tests in place? Do they test a minimal set of functionality and leave the gui as close as possible to its original state?
• Has the manual system tests spreadsheet been updated?
  • Manual system tests for the functionality should be added if there are no automated tests
  • Manual system tests can be removed from the template if they are covered by suitable automated tests
• Did any existing system test break as a result of the current changes?
• Have the changes been documented in the release notes. If so, do they describe the changes appropriately?
• If an OPI has been modified, does it conform to the style guidelines? There is a script called check_opi_format.py to help with this.

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed.
• How do the changes handle unexpected situations, e.g. bad input?
• Has developer documentation been updated if required?

Final Steps

• Reviewer has moved the release notes entry for this ticket in the "Changes merged into master" section

[DominicOram]

Can you do the same for setSetupSource as I imagine a similar issue could happen here?