UnboundLocalError in Dungeon Game

import os
import random

# draw grid
#pick random location for player
# for player
#monster
#draw player in the grid
#take input for movment
#move player, unless incalid move(past edges of grid)
#check for win/loss
#clear screen and redraw grid

CELLS = [(0,0),(1,0),(2,0),(3,0),(4,0),
         (0,1),(1,1),(2,1),(3,1),(4,1),
         (0,2),(1,2),(2,2),(3,2),(4,2),
         (0,3),(1,3),(2,3),(3,3),(4,3),
         (0,4),(1,4),(2,4),(3,4),(4,4),]


def clear_screen():
    os.system('cls'if os.name == 'nt'else 'clear')


def get_locations():
    return random.sample(CELLS, 3)


def move_player(player,move):
    x,y = player
    if move == "LEFT":
        x -= 1
    if move == "RIGHT":
        x += 1
    if move == "UP":
        y -= 1
    if move == "DOWN":
        y += 1
    return x,y


def get_moves(player):
    moves = ["LEFT","RIGHT","UP","DOWN"]
    x,y = player
    if x == 0:
        moves.remove("LEFT")
    if x == 4:
        moves.remove("RIGHT")
    if y == 0:
        moves.remove("UP")
    if y == 4:
        moves.remove("DOWN")
    return moves


def draw_map(player):
    print(" _"*5)
    tile = "|{}"

    for cell in CELLS:
        x,y = cell
        if x < 4:
            line_end = ""
            if cell == player:
                output = tile.format("X")
            else:
                out = tile.format("_")
        else:
            line_end = "\n"
            if cell == player:
                output = tile.format("X|")
            else:
                output = tile.format("_|")
        print(output, end = line_end)


def game_loop():
    monster, door, player = get_locations()

    while True:
        draw_map(player)
        valid_moves = get_moves(player)

        print("You're currently in room {}".format(player))
        print("You can move {}".format(", ".join(valid_moves)))
        print("Enter QUIT to quit")

        move = input("> ")
        move = move.upper()

        if move == 'QUIT':
            break
        if move in valid_moves:
            player = move_player(player,move)
        else:
            input("\n ** Walls are hard! Don't run into them! **\n")
        clear_screen()


clear_screen()
print("Welcome to the dungeon!")
input("Press return to start!")
clear_screen()
game_loop()