Godot 3.1 Invalid get'index '16' (on base:Array) - arrays

Question

Invalid get'index '16' (on base:Array).
Hi Im getting the above message when the player attempts to moves outside of the
array size (tile size).
The error occurs on line 54:
grid[new_grid_pos.x][new_grid_pos.y] = ENTITY_TYPES.PLAYER
Im stuck on how to fix it.
regards
Jason
extends TileMap
var tile_size = get_cell_size()
var half_tile_size = tile_size / 2
enum ENTITY_TYPES {PLAYER, OBSTACLE, COLLECTIBLE}
var grid_size = Vector2(16,16)
var grid = []
onready var Obstacle = preload("res://scenes/Obstacle.tscn")
func _ready():
# Creates grid array of grid_size
for x in range(grid_size.x):
grid.append([])
for y in range(grid_size.y):
grid[x].append(null)
print(ENTITY_TYPES)
# Create obstacle positions array
var positions = []
# create 5 obstacles
for n in range(5):
# random positions constrained to grid_size
var grid_pos = Vector2(randi() % int(grid_size.x),randi() % int(grid_size.y))
#check random posisitions not already in array before adding new one
if not grid_pos in positions:
positions.append(grid_pos)
for pos in positions:
var new_obstacle = Obstacle.instance()
new_obstacle.position = (map_to_world(pos) + half_tile_size)
grid[pos.x][pos.y] = ENTITY_TYPES.OBSTACLE
add_child(new_obstacle)
func is_cell_vacant(pos, direction):
# Return true if cell is vaccant, else false
var grid_pos = world_to_map(pos) + direction
# world Boundaries
if grid.pos.x < grid_size.x and grid_pos.x >= 0:
if grid.pos.y < grid_size.y and grid_pos.y >= 0:
#return true if grid[grid_pos.x][grid_pos.y] == null else false
return grid[grid_pos.x][grid_pos.y] == null
return false
func update_child_pos(child_node):
# Move a child to a new position in the grid array
# Returns the new target world position of the child
var grid_pos = world_to_map(child_node.position)
grid[grid_pos.x][grid_pos.y] = null
var new_grid_pos = grid_pos + child_node.direction
grid[new_grid_pos.x][new_grid_pos.y] = ENTITY_TYPES.PLAYER
var target_pos = (map_to_world(new_grid_pos) + half_tile_size)
return target_pos
pass

Answer 1

You are receiving the error because you are exceeding the arrays elements.
To avoid it, either make the grid bigger or make it so that the player cannot leave the grid.
If you want the player to be able to leave the grid, then you will probably have to create an if condition:
if player_in_grid: grid[new_grid_pos.x][new_grid_pos.y] = ENTITY_TYPES.PLAYER.