Created lane feature that should be backwards compatible with non-lane features

src/classes/spearhead_events.lua

@@ -29,7 +29,7 @@ do
     end
 
     ---@class OnStageChangedListener
-    ---@field OnStageNumberChanged fun(self:OnStageChangedListener, number:integer)
+    ---@field OnStageNumberChanged fun(self:OnStageChangedListener, number:integer, laneIdentifier:string?)
 
     do -- STAGE NUMBER CHANGED
         local OnStageNumberChangedListeners = {}
@@ -37,17 +37,11 @@ do
         ---Add a stage zone number changed listener
         ---@param listener OnStageChangedListener object with function OnStageNumberChanged(self, number)
         SpearheadEvents.AddStageNumberChangedListener = function(listener)
-            table.insert(OnStageNumberChangedListeners, listener)
-        end
-
-        ---Add a stage zone number changed listener
-        ---@param handler function function(number)
-        SpearheadEvents.AddStageNumberChangedHandler = function(handler)
-            if type(handler) ~= "function" then
-                warn("Event handler not of type function, did you mean to use listener?")
+            if type(listener) ~= "table" or type(listener.OnStageNumberChanged) ~= "function" then
+                warn("Event handler not of type table/object with function OnStageNumberChanged(self, number)")
                 return
             end
-            table.insert(OnStageNumberChangedHandlers, handler)
+            table.insert(OnStageNumberChangedListeners, listener)
         end
 
         ---@class OnStageNumberChangeCompleteListener
@@ -64,14 +58,15 @@ do
         end
 
         ---@param newStageNumber number
-        SpearheadEvents.PublishStageNumberChanged = function(newStageNumber)
+        ---@param laneIdentifier string?
+        SpearheadEvents.PublishStageNumberChanged = function(newStageNumber, laneIdentifier)
             pcall(function ()
                 Persistence.SetActiveStage(newStageNumber)
             end)
 
             for _, callable in pairs(OnStageNumberChangedListeners) do
                 local succ, err = pcall(function()
-                    callable:OnStageNumberChanged(newStageNumber)
+                    callable:OnStageNumberChanged(newStageNumber, laneIdentifier)
                 end)
                 if err then
                     logError(err)
@@ -79,7 +74,7 @@ do
             end
 
             for _, callable in pairs(OnStageNumberChangedHandlers) do
-                local succ, err = pcall(callable, newStageNumber)
+                local succ, err = pcall(callable, newStageNumber, laneIdentifier)
                 if err then
                     logError(err)
                 end