Yes it is potential bug in blueprint data or blueprint corruption, first could you post screen of blueprint that may cause htis error (look on which blueprint was packaged when error popup)
Information in log before this error:
LogBlueprint:Warning: USimpleConstructionScript::FixupRootNodeParentReferences() - Couldn’t find inherited parent component ‘DefaultSceneRoot’ for ‘Weapon’ in BlueprintGeneratedClass ‘REINST_Weapon_C_54’ (it may have been removed)
LogBlueprint:Warning: USimpleConstructionScript::FixupRootNodeParentReferences() - Couldn’t find inherited parent component ‘DefaultSceneRoot’ for ‘Sphere’ in BlueprintGeneratedClass ‘REINST_Ammo_Bullets_C_71’ (it may have been removed)
Can you provide the entire output log from the package attempt? Also, as pointed out, posting a screenshot of the blueprint that may have caused the error would help in identifying why it is failing to compile.