Fix dungeon margin bug (#4276)

Some mapgen settings used to crash the game.

Reviewed-on: https://git.minetest.land/MineClone2/MineClone2/pulls/4276
Reviewed-by: Mikita Wiśniewski <rudzik8@protonmail.com>
Co-authored-by: Bram van den Heuvel <bram.vdh1999@gmail.com>
Co-committed-by: Bram van den Heuvel <bram.vdh1999@gmail.com>

mods/ENTITIES/mcl_mobs/init.lua

@@ -374,7 +374,7 @@ function mcl_mobs.register_arrow(name, def)
 		rotate = def.rotate,
 		on_punch = def.on_punch or function(self, puncher, time_from_last_punch, tool_capabilities, dir, damage)
 			local vel = self.object:get_velocity():length()
-			self.object:set_velocity({x=dir.x * vel, y=dir.y * vel, z=dir.z * vel})
+			self.object:set_velocity(dir * vel)
 			self._puncher = puncher
 		end,
 		collisionbox = def.collisionbox or {0, 0, 0, 0, 0, 0},

mods/ENTITIES/mobs_mc/ghast.lua

@@ -126,13 +126,14 @@ mcl_mobs.register_arrow("mobs_mc:fireball", {
 	end,
 
 	hit_mob = function(self, mob)
+		local name = mob:get_luaentity().name
 		mob:punch(self.object, 1.0, {
 			full_punch_interval = 1.0,
 			damage_groups = {fleshy = 6},
 		}, nil)
 		mcl_mobs.mob_class.boom(self,self.object:get_pos(), 1, true)
 		local ent = mob:get_luaentity()
-		if not ent or ent.health <= 0 then
+		if (not ent or ent.health <= 0) and self._puncher and name == "mobs_mc:ghast" then
 			awards.unlock(self._puncher:get_player_name(), "mcl:fireball_redir_serv")
 		end
 	end,

mods/MAPGEN/mcl_dungeons/init.lua

@@ -406,6 +406,8 @@ local function dungeons_nodes(minp, maxp, blockseed)
 	local pr = PseudoRandom(blockseed)
 	for a=1, attempts do
 		local dim = dungeonsizes[pr:next(1, #dungeonsizes)]
+
+		if ymin <= ymax - dim.y - 1 then
 			local x = pr:next(minp.x, maxp.x-dim.x-1)
 			local y = pr:next(ymin  , ymax  -dim.y-1)
 			local z = pr:next(minp.z, maxp.z-dim.z-1)
@@ -415,6 +417,7 @@ local function dungeons_nodes(minp, maxp, blockseed)
 			emerge_area(p1, p2, ecb_spawn_dungeon, {p1=p1, p2=p2, dim=dim, pr=pr})
 		end
 	end
+end
 
 function mcl_dungeons.spawn_dungeon(p1, _, pr)
 	if not p1 or not pr or not p1.x or not p1.y or not p1.z then return end