Fix OOB acces in OutStreamSeq when service enabled but unused

Fix for the setup when OutputStreamSequencer is configured and enabled but not actually used that would SEGV.

changed the description

This merge request affects 1 package:

• Control/AthenaServices

Adding @ssnyder as watcher

added Core master review-pending-level-1 labels

CI Result SUCCESS (hash 15d1a598)

	Athena	AthSimulation	AnalysisBase	AthGeneration
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 16419]

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit c286b16d

added sweep:ignore label