NullReferenceException thrown can in rare occasions cause passengers to get stuck

Passengiers seems to be stuck in the secure zone, without any flights to board. All flights already left and none incomming untill the next day.

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COLLECTED HARDWARE DATA
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Device
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Model: All Series (ASUS)

Operating system: Windows 10 (10.0.0) 64bit

RAM size: 8 GB

Battery status: Charging
Battery level: -1

Processor Device
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Type: Intel(R) Core(TM) i5-4460 CPU @ 3.20GHz
Core count: 4
Frequency: 3 GHz

Grahpics Device
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Vendor: NVIDIA
Type: NVIDIA GeForce 9600 GT
Memory Size: 2 GB

Screen Summary
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Full Screen: True
Resolution: 1280 x 800 @ 32Hz