Fix g.change() type checking

[rerpha]

Description of work

By making it less clever. evidently this is also less lines of code...

To test

See ISISComputingGroup/IBEX#8849

Acceptance criteria

see ticket.

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Code Review

• Is the code of an acceptable quality?
• Are there unit tests in place? Are the unit tests small and test the a class in isolation?
• Have the changes been documented in the release notes. If so, do they describe the changes appropriately?

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?

[Tom-Willemsen]

ew