Don't crash if level schematic is missing

mods/lzr_editor/init.lua

@@ -348,19 +348,6 @@ minetest.register_chatcommand("editor_save", {
 	end,
 })
 
--- Returns true if the given file exists, false otherwise.
--- * path: Path to file (without file name)
--- * filename: File name of file (without path)
-local file_exists = function(path, filename)
-	local levels = minetest.get_dir_list(path, false)
-	for l=1, #levels do
-		if levels[l] == filename then
-			return true
-		end
-	end
-	return false
-end
-
 local load_level = function(level_name, player)
 	if lzr_gamestate.get_state() ~= lzr_gamestate.EDITOR then
 		return false
@@ -370,7 +357,7 @@ local load_level = function(level_name, player)
 		return false
 	end
 	local filename = level_name..".mts"
-	local ok = file_exists(minetest.get_worldpath().."/levels", filename)
+	local ok = lzr_util.file_exists(minetest.get_worldpath().."/levels", filename)
 	if not ok then
 		return false
 	end
@@ -517,7 +504,7 @@ minetest.register_chatcommand("editor_load", {
 		if check_for_slash(level_name) then
 			return false, S("Level name must not contain slash or backslash!")
 		end
-		local ok = file_exists(minetest.get_worldpath().."/levels", level_name..".mts")
+		local ok = lzr_util.file_exists(minetest.get_worldpath().."/levels", level_name..".mts")
 		if not ok then
 			return false, S("Level file does not exist!")
 		end

mods/lzr_editor/mod.conf

@@ -1,2 +1,2 @@
 name = lzr_editor
-depends = lzr_gamestate, lzr_levels, lzr_gui, lzr_player, lzr_node_drops, lzr_ambience, lzr_getitem, lzr_csv, lzr_globals, lzr_privs, lzr_weather, lzr_tools, lzr_hook, lzr_teleporter, lzr_treasure, lzr_mapgen, lzr_world, lzr_triggers
+depends = lzr_gamestate, lzr_levels, lzr_gui, lzr_player, lzr_node_drops, lzr_ambience, lzr_getitem, lzr_csv, lzr_globals, lzr_privs, lzr_weather, lzr_tools, lzr_hook, lzr_teleporter, lzr_treasure, lzr_mapgen, lzr_world, lzr_triggers, lzr_util

mods/lzr_level_select/init.lua

@@ -121,7 +121,9 @@ local load_custom_level = function(level, player)
 		local error_append = ""
 		if error_detail then
 			local reason
-			if error_detail == "no_teleporter" then
+			if error_detail == "file_nonexistant" then
+				reason = S("The level schematic file chould not be found.")
+			elseif error_detail == "no_teleporter" then
 				reason = S("There’s no teleporter for the player to start on.")
 			elseif error_detail == "too_many_teleporters" then
 				reason = S("There’s more than one teleporter.")
@@ -133,6 +135,8 @@ local load_custom_level = function(level, player)
 				reason = S("There’s a bare gold block in the level.")
 			elseif error_detail == "plant_on_ground" then
 				reason = S("There’s a rooted plant in the level.")
+			elseif error_detail == "schematic_load_error" then
+				reason = S("Error while loading schematic file.")
 			else
 				reason = error_detail
 			end

mods/lzr_levels/init.lua

@@ -95,9 +95,14 @@ local flat_index_to_pos = function(index, size)
 end
 
 local analyze_level_schematic = function(filename, levels_path, level_data_entry)
+	if not lzr_util.file_exists(levels_path, filename) then
+		return false, "file_nonexistant"
+	end
 	local filepath = levels_path .. "/" ..filename
 	local schem = minetest.read_schematic(filepath, {write_yslice_prob="none"})
-	assert(schem, "Could not load level file: "..filename)
+	if not schem then
+		return false, "schematic_load_error"
+	end
 	level_data_entry.contains_rotatable_block = false
 	level_data_entry.treasures = 0
 	level_data_entry.size = schem.size

mods/lzr_levels/mod.conf

@@ -1,2 +1,2 @@
 name = lzr_levels
-depends = lzr_core, lzr_mapgen, lzr_globals, lzr_hook, lzr_gamestate, lzr_ambience, lzr_csv, lzr_weather, lzr_laser, lzr_treasure, lzr_world, lzr_triggers, lzr_slowdown
+depends = lzr_core, lzr_mapgen, lzr_globals, lzr_hook, lzr_gamestate, lzr_ambience, lzr_csv, lzr_weather, lzr_laser, lzr_treasure, lzr_world, lzr_triggers, lzr_slowdown, lzr_util

mods/lzr_util/init.lua

@@ -83,3 +83,16 @@ lzr_util.hsv_to_rgb = function(h, s, v)
 
         return math.floor(r * max_value), math.floor(g * max_value), math.floor(b * max_value)
 end
+
+-- Returns true if the given file exists, false otherwise.
+-- * path: Path to file (without file name)
+-- * filename: File name of file (without path)
+lzr_util.file_exists = function(path, filename)
+	local levels = minetest.get_dir_list(path, false)
+	for l=1, #levels do
+		if levels[l] == filename then
+			return true
+		end
+	end
+	return false
+end