Fixed Badeline last node crash (#657)

Co-authored-by: DemoJameson <[email protected]>

Celeste.Mod.mm/Content/Dialog/English.txt

@@ -27,6 +27,7 @@
 	POSTCARD_MISSINGTUTORIAL=	{big}Oops!{/big}{n}The playback tutorial {#ff1144}((tutorial)){#} could not be found.{n}Check your {#44adf7}log.txt{#} for more info.
 	POSTCARD_TILEXMLERROR=		{big}Oops!{/big}{n}There was an error parsing a tileset in {#ff1144}((path)){#}{n}Check your {#44adf7}log.txt{#} for more info.
 	POSTCARD_XMLERROR=			{big}Oops!{/big}{n}{#ff1144}((path)){#} has a syntax error.{n}Check your {#44adf7}log.txt{#} for more info.
+	POSTCARD_BOSSLASTNODEHIT=	{big}Oops!{/big}{n}{#ff1144}Badeline Boss{#} entity was hit on its last node, please add an additional node outside of the current room to ensure the player never hits it.
 
 # Main Menu
 	MENU_TITLETOUCH= 		TOUCH

Celeste.Mod.mm/Patches/FinalBoss.cs

@@ -1,6 +1,8 @@
 #pragma warning disable CS0626 // Method, operator, or accessor is marked external and has no attributes on it
+#pragma warning disable CS0649 // Field is never assigned to, and will always have its default value
 
 using System;
+using Celeste.Mod;
 using Microsoft.Xna.Framework;
 using Mono.Cecil;
 using Mono.Cecil.Cil;
@@ -13,6 +15,10 @@ class patch_FinalBoss : FinalBoss {
 
         private bool canChangeMusic;
 
+        private int nodeIndex;
+
+        private Vector2[] nodes;
+
         public patch_FinalBoss(EntityData e, Vector2 offset)
             : base(e, offset) {
             // no-op. MonoMod ignores this - we only need this to make the compiler shut up.
@@ -30,14 +36,29 @@ public void ctor(EntityData data, Vector2 offset) {
         [PatchBadelineBossOnPlayer] // ... except for manually manipulating the method via MonoModRules
         public new extern void OnPlayer(Player player);
 
+        private extern void orig_PushPlayer(Player player);
+
+        private void PushPlayer(Player player) {
+            // ensure we are not hitting the last node
+            if (nodeIndex >= nodes.Length) {
+                Logger.Log(LogLevel.Warn, "FinalBoss",
+                    "FinalBoss entity was hit on its last node, please add an additional node outside of the current room to ensure the player never hits it.");
+                patch_LevelEnter.ErrorMessage = Dialog.Get("postcard_bosslastnodehit");
+
+                // we want to call LevelEnter.Go explicitly instant of letting CheckForErrors call it to prevent double triggers of postcard
+                LevelEnter.Go((Scene as Level).Session, false);
+            } else {
+                orig_PushPlayer(player);
+            }
+        }
+
         public bool CanChangeMusic(bool value) {
             Level level = Scene as Level;
             if (level.Session.Area.GetLevelSet() == "Celeste")
                 return value;
 
             return canChangeMusic;
         }
-
     }
 }