fix some references to null pointers

[rlcee]

fsanitize test finds pointers that were not created were dereferenced. The pointers were not created because they were inside version checks, but this use was outside the version checks. This commit just moves the dereference to within version checks.

[FNALbuild]

Hi @rlcee,
You have proposed changes to files in these packages:

• Mu2eG4

which require these tests: build.

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@resnegfk

⌛ The following tests have been triggered for ae117da: build (Build queue is empty)

About FNALbuild. Code review on Mu2e/Offline.

[FNALbuild]

☀️ The tests passed at ae117da.

Test	Result	Details
merge	✅	Merged ae117da at a62d09b
build (prof)	✅	Log file. Build time: 27 min 37 sec
ceSimReco	✅	Log file.
g4test_03MT	✅	Log file.
transportOnly	✅	Log file.
POT	✅	Log file.
g4study	✅	Log file.
cosmicSimReco	✅	Log file.
cosmicOffSpill	✅	Log file.
ceSteps	✅	Log file.
ceDigi	✅	Log file.
muDauSteps	✅	Log file.
ceMix	✅	Log file.
rootOverlaps	✅	Log file.
g4surfaceCheck	✅	Log file.
FIXME, TODO	✅	TODO (0) FIXME (0) in 1 files
clang-tidy	〰️	0 errors 0 warnings

N.B. These results were obtained from a build of this Pull Request at ae117da after being merged into the base branch at a62d09b.

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[kutschke]

This is straightforward. Thanks for looking after it.