Fix crashes:

1. when train hit a route, nil access to already cancelled route caused crash
2. fix crash when trying to ensure_init a train that doesn't exist

advtrains/trainlogic.lua

@@ -222,6 +222,12 @@ local callbacks_remove, run_callbacks_remove = mkcallback("remove")
 -- - save files were loaded
 -- Additionally, this gets called outside the step cycle to initialize and/or remove a train, then occ_write_mode is set.
 function advtrains.train_ensure_init(id, train)
+	if not train then
+		atwarn("train_ensure_init: Called with id =",id,"but a nil train!")
+		atwarn(debug.traceback())
+		return nil
+	end
+	
 	train.dirty = true
 	if train.no_step then return nil end
 

advtrains_interlocking/train_sections.lua

@@ -85,7 +85,7 @@ local function setsection(tid, train, ts_id, ts, sigd)
 			atwarn("Train",tid,"hit route",ts.route.rsn,"!")
 			advtrains.interlocking.route.cancel_route_from(ts.route.origin)
 			atwarn("Route was cancelled.")
-		end
+		else
 			-- train entered route regularily. Reset route and signal
 			tcbs.route_committed = nil
 			tcbs.route_comitted = nil -- TODO compatibility cleanup
@@ -100,6 +100,7 @@ local function setsection(tid, train, ts_id, ts, sigd)
 					tcbs.routeset = nil
 				end
 			end
+		end
 		ts.route = nil
 	end
 	if tcbs.signal then