Guard null bastion group in the BSI overlay

[grepsedawk]

Problem

NameLayer spams the console with a full stack trace on every player move:

[NameLayer] hasAccess failed, caller passed in null
java.lang.Exception: null
    at GroupManager.hasAccess(GroupManager.java:438)
    at ModeListener.updateDisplayedInformation(ModeListener.java:113)
    at ModeListener.onPlayerMove(ModeListener.java:83)

Root cause

The BSI overlay calls hasAccess(bastion.getGroup(), ...) for each blocking bastion. getGroup() returns null when the bastion's reinforcement isn't loaded — its block sits on an unloaded chunk at the field edge while the field still covers the moving player. NameLayer's hasAccess treats a null group as a caller bug and logs new Exception() at INFO, so every qualifying move event prints a stack trace.

Fix

Resolve the group once and skip the hasAccess call when it's null, classifying the bastion as not-allied directly. Display behaviour is unchanged — an unresolved group already fell into the enemy bucket — it just no longer routes a null through hasAccess.

Notes

• A companion change in NameLayer's hasAccess makes a null group a quiet deny (a null perm is still logged as a real caller bug); this Bastion guard is defense-in-depth on the caller side and also avoids the redundant lookup.
• Out of scope: GroupManager.getGroup(int) still does a synchronous DB query on the main thread on cache miss.