Add empty collection guard in TimeAndPhiClusterFinder::findTimePeaks

[oksuzian]

No description provided.

[FNALbuild]

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

• TrkPatRec

which require these tests: build.

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⌛ The following tests have been triggered for 99412e9: build (Build queue - API unavailable)

About FNALbuild. Code review on Mu2e/Offline.

[FNALbuild]

☀️ The build tests passed at 99412e9.

Test	Result	Details
test with	✅	Command did not list any other PRs to include
merge	✅	Merged 99412e9 at db6161d
build (prof)	✅	Log file. Build time: 04 min 09 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.
trigger	✅	Log file.
check_cmake	✅	Log file.
FIXME, TODO	✅	TODO (0) FIXME (0) in 1 files
clang-tidy	➡️	2 errors 46 warnings
whitespace check	✅	no whitespace errors found

N.B. These results were obtained from a build of this Pull Request at 99412e9 after being merged into the base branch at db6161d.

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[rlcee]

Given the following line, this is obviously necessary, but I can't comment whether chGood can legitimately be empty at this point.