Potential soft-lock during point-blank shot from hidden unit

[gsparks3]

Prerequisites and Pre-Issue Checklist

• I'm reporting the issue to the correct repository:

• MegaMek

• MegaMekLab

• MekHQ

• I've tested the issue against at least the latest MILESTONE version

• I've asked on the MegaMek Discord about the error

• I've reviewed the BattleTech rules and MegaMek documentation, and I've confirmed that something isn't working as intended.

• I've searched the Github tracker and haven't found the issue listed

Severity *

High (Major Disruption): A major feature is broken or incorrect, but a workaround exists.

Brief Description *

If a point-blank shot from a hidden unit is triggered, and the player of the hidden unit chooses to take the point-blank shot when prompted, but the hidden unit in question is incapable of attacking the unit that triggered the PBS, the game soft-locks. The "Skip Firing" button is available, but does not appear to do anything.

Severity is a little tricky on this one - the error is currently unrecoverable once it occurs (short of reloading from an earlier autosave, which is highly inconvenient, especially in games with a lot of units), but encountering a situation where it occurs is relatively rare. Not using hidden units will avoid it entirely, and choosing not to take the point-blank shot will also avoid the soft-lock in the case that the hidden unit would not be able to attack the triggering unit (which is itself uncommon).

This bug was initially encountered when an airborne aerospace fighter triggered a point-blank shot from a hidden infantry unit, but it is arguable whether airborne aerospace units should detect hidden units at all, so the provided save reproduces an equivalent issue with two mechs instead.

Steps to Reproduce

1. Load the provided save as AmbushVictim. Connect an additional client as HiddenUnit.
2. Walk the Locust southwest five hexes.
3. Click "Yes" on the PBS prompt on the HiddenUnit client.
4. Observe that the target is fully out of arc, so no fire can be declared to allow Done Firing to be pressed.
5. Observe that pressing Skip Firing has no effect.

Operating System *

Windows 10

Java Version *

17.0.11

MegaMek Suite Version *

v0.49.19.1

Custom MegaMek Version

No response

Attach Files

hidden_unit_softlock_test.sav.gz

Final Checklist

• I've checked to make sure that this issue has not already been filed
• I'm reporting only one issue in this ticket for clarity and focus