fix(jumanji): prevent IndexError in routing render when no valid nodes

[hobostay]

Summary

Fix an IndexError in the Jumanji routing renderer's build_edges() method that crashes when an agent has no valid connected nodes.

Root Cause

In envpool/jumanji/_official_render/routing.py line 656:

len_conn = np.where(conn_group != -1)[0][-1]

When conn_group contains only -1 values (no valid connected nodes for an agent), np.where(conn_group != -1)[0] returns an empty array. Accessing [-1] on an empty array raises IndexError.

Fix

Add a guard to check if there are valid indices before proceeding:

valid_indices = np.where(conn_group != -1)[0]
if len(valid_indices) == 0:
    continue
len_conn = valid_indices[-1]

Test plan

• Verify rendering works when all agents have valid connected nodes
• Verify no crash when an agent has no valid connected nodes