fix: reports page — add asset lat/lng to /api/visits for map button, fix null field guard in form error handler

server.py

@@ -2611,7 +2611,7 @@ def list_visits(
         params.append(date_to + " 23:59:59")
 
     where = " AND ".join(conditions)
-    sql = """SELECT v.*, a.name AS asset_name, a.machine_id,
+    sql = """SELECT v.*, a.name AS asset_name, a.machine_id, a.latitude, a.longitude,
                     u.username AS user_name
              FROM visits v
              LEFT JOIN assets a ON v.asset_id = a.id