[BUG] (121.4) The game freezes when trying to upgrade Conveyor track in a specific situation

[qrss]

Platform: Windows

Build: steam build 121.4

Issue: I tried to upgrade my Conveyor belt track to Titanium and the game froze. After some time I got the java.lang.OutOfMemoryError: Java heap space error.

I can reproduce this every time in my game save. I tried to create the same crash as a minimal example in a blank sandbox game, but failed, so I have no idea what the exact cause of this is. If you load up my attached Campaign save, hopefully you should be able the reproduce the crash.

Probably an edge case in some algorithm, so nothing serious if I'm the first to encounter this.

Steps to reproduce: See the following GIF or the instructions after the GIF. I have tried over 5 times and reproduced it 100% of the time by going through the following steps.

0. Open the campaign and go to Fungal Wastes.
1. Select a Titanium Conveyor for building.
2. Put the mouse over the Titanium Conveyor near your ship that is already built.
3. Press and hold down Control.
4. Press and hold down Left Mouse Button.
5. Move your mouse cursor one square to the right in an attempt to upgrade your Conveyor track to Titanium.
6. The game freezes.
7. While the game is frozen, the memory usage of the game grows until the game crashes (java.lang.OutOfMemoryError: Java heap space) with the attached Crash Log.

Link(s) to mod(s) used: None.

Save file: saves.zip

(Crash) logs: crash-report-12_16_2020_22_03_39.txt

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Place an X (no spaces) between the brackets to confirm that you have read the line below.

• [X] I have updated to the latest release (https://github.com/Anuken/Mindustry/releases) to make sure my issue has not been fixed.
• [X] I have searched the closed and open issues to make sure that this problem has not already been reported.

[qrss]

Wow, that was quick.

Good job!