Fix crashes, fix link in documentation

mods/ENTITIES/mcl_minecarts/DOC.md

@@ -33,7 +33,7 @@ Processing for minecart movement is as follows:
    4. The cart checks for nearby carts and collides elastically with these. The
       calculations for these collisions are in the function `handle_cart_collision`
    5. If the cart enters a new block, determine the new direction the cart will
-      move with `mcl_minecarts:get_rail_direction` in [functions.lua](./functions.lua].
+      move with `mcl_minecarts:get_rail_direction` in [functions.lua](./functions.lua).
       The rail nodes provide a hook `_mcl_minecarts.get_next_direction` that
       provides this information based on the previous movement direction.
 3. If an entity exists for a given cart, the entity will update its position

mods/ENTITIES/mcl_minecarts/init.lua

@@ -5,7 +5,7 @@ local mod = mcl_minecarts
 mcl_minecarts.modpath = modpath
 
 -- Constants
-mod.speed_max = 10
+mod.SPEED_MAX = 10
 mod.FRICTION = 0.4
 mod.MAX_TRAIN_LENGTH = 4
 mod.CART_BLOCK_SIZE = 64

mods/ENTITIES/mcl_minecarts/movement.lua

@@ -240,7 +240,6 @@ local function calculate_acceleration(staticdata)
 	local pos = staticdata.connected_at
 	local node_name = minetest.get_node(pos).name
 	local node_def = minetest.registered_nodes[node_name]
-	local max_vel = SPEED_MAX
 
 	local ctrl = staticdata.controls or {}
 	local time_active = minetest.get_gametime() - 0.25
@@ -251,7 +250,7 @@ local function calculate_acceleration(staticdata)
 		acceleration = -1.5
 	elseif (staticdata.fueltime or 0) > 0 and staticdata.velocity <= 4 then
 		acceleration = 0.6
-	elseif staticdata.velocity >= ( node_def._max_acceleration_velocity or max_vel ) then
+	elseif staticdata.velocity >= ( node_def._max_acceleration_velocity or SPEED_MAX ) then
 		-- Standard friction
 	elseif node_def and node_def._rail_acceleration then
 		acceleration = node_def._rail_acceleration * 4

mods/ENTITIES/mcl_minecarts/storage.lua

@@ -3,6 +3,7 @@ local mod = mcl_minecarts
 
 -- Imports
 local CART_BLOCK_SIZE = mod.CART_BLOCK_SIZE
+assert(CART_BLOCK_SIZE)
 
 local cart_data = {}
 local cart_data_fail_cache = {}
@@ -72,9 +73,9 @@ function mod.find_carts_by_block_map(block_map)
 	return cart_list
 end
 
-function mod.add_block_map(block_map, min_pos, max_pos)
-	local min = vector.floor(vector.divide(min_pos), CART_BLOCK_SIZE)
-	local max = vector.floor(vector.divide(max_pos), CART_BLOCK_SIZE) + vector.new(1,1,1)
+function mod.add_blocks_to_map(block_map, min_pos, max_pos)
+	local min = vector.floor(vector.divide(min_pos, CART_BLOCK_SIZE))
+	local max = vector.floor(vector.divide(max_pos, CART_BLOCK_SIZE)) + vector.new(1,1,1)
 	for z = min.z,max.z do
 		for y = min.y,max.y do
 			for x = min.x,max.x do