TruthConverters+TruthIO: fix cppcheck defects

Fix potential nullptr deref and uninitialized variables.

This merge request affects 2 packages:

• Generators/TruthConverters
• Generators/TruthIO

Affected files list will not be printed in this case

added Generators main review-pending-level-1 labels

CI Result SUCCESS (hash 38630d42)

	Athena	AthGeneration
externals
cmake
make
tests

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Athena: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
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removed review-pending-level-1 label

added review-approved label

merged

mentioned in commit ad5f48c4