Rec-Vend Pen entry duplication

[mesnomer]

Testmerges

#5724: 'XM43E1 in regular gameplay' by Releasethesea at commit d6f45c8 #5763: 'Map: Bigred change south lambda padlock and turned it into a checkpoint.' by Huffie56 at commit 646c477 #5829: 'Event borers' by realforest2001 at commit dee964d #5950: 'Med Skill Rebalance Mk2 Demon Free Edition' by Katskan at commit 9f4b9db #5006: 'Project ARES: Added Tech Unlock logs' by realforest2001 at commit c0645ab #5401: 'M540-A Armored Recon Carrier' by Zonespace27 at commit 9be4807 #5925: 'Biosuit Updates' by realforest2001 at commit bf9853d #5946: 'Autocompressor Efficiency Increase' by Katskan at commit 93e4247

Round ID

21360

Description of the bug

Hacking a Rec-Vend and switching between Products and Contraband tabs duplicates the entry for pens. They show up in both tabs and purchasing them does not reduce the listed stock -- they always show as having 10 left. Closing the vendor window resets this.

I then disabled the ID scanner to try buying a bunch, and started getting a "The Rec-Vend beeps, "Sold out of data."" message.

What's the difference with what should have happened?

Less pens, presumably.

How do we reproduce this bug?

1. Screwdriver Rec-Vend
2. Pulse Inventory Control
3. Switch tabs
4. Switch tabs again
5. Disrupt the BIC monopoly

Issue Bingo

• Issue could be reproduced at least once
• Issue happened in a recent (less than 7 days ago) round
• Couldn't find an existing issue about this (https://github.com/cmss13-devs/cmss13/issues)