example code from CoffeeScript by Trevor Burnham with a few errors left in of my own making.

game.coffee

MIN_WORD_LENGTH = 2
GRID_SIZE = 5
inRange = (x, y) ->
	0 <= x < GRID_SIZE and 0 <= y < GRID_SIZE
fs = require 'fs'
owl2 = fs.readFileSync 'OWL2.txt', 'utf8'
wordList = owl2.match /^(\w+)/mg
wordList = (word for word in wordList when word.length <= GRID_SIZE)
isWord = (string) ->
	string in wordList
# taken from scrabble
tileCounts =
	A: 9, B: 2, C: 2, D: 4, E: 12, F: 2, G: 3, H: 2, I: 9, J: 1, K: 1, L: 4, M: 2, N: 6, O: 8, P: 2, Q: 1, R: 6, S: 4, T: 6, U: 4, V: 2, W: 2, X: 1, Y: 2, Z: 1
totalTiles = 0
totalTiles += count for letter, count of tileCounts
alphabet = (letter for letter of tileCounts).sort()
randomLetter = ->
	randomNumber = Math.ceil Math.random() * totalTiles
	x = 1
	for letter in alphabet
		x += tileCounts[letter]
	return letter if x > randomNumber
# grid is a 2D array: grid[col][row], where 0, 0 is the upper-left corner
grid = for x in [0...GRID_SIZE]
	for y in [0...GRID_SIZE]
		randomLetter()
printGrid = ->
	#Transpose the grid so we can draw rows
	rows = for x in [0...GRID_SIZE]
		for y in [0...GRID_SIZE]
			grid[y][x]
	rowStrings = (' ' + row.join(' | ') for row in rows)
	rowSeparator = ('-' for i in [1...GRID_SIZE * 4]).join('')
	console.log '|n' + rowStrings.join("\n#{rowSeparator}\n") + '\n'
tileValues =
	A: 1, B: 3, C:3, D:2, E:1, F:4, G:2, H:4, I:1, J:8, K:5, L:1, M:3, N:1, O:1, P:3, Q:10, R:1, S:1, T:1, U:1, V:4, W:4, X:8, Y:4, Z:10
moveCount = 0
score = 0
usedWords = []
#scoring function
scoreMove = (grid, swapCoordinates) ->
	{x1, x2, y1, y2} = swapCoordinates
	# error happens on this line
	words = wordsThroughTile(grid, x1, y1).concat wordsThroughTile(grid, x2, y2)
	moveScore = multiplier = 0
	newWords = []
	for word in words when word not in usedWords and word not in newWords
		multiplier++
		moveScore += tileValues[letter] for letter in word
		newWords.push word
	usedWords = usedWords.concat newWords
	moveScore *= multiplier
	{moveScore, newWords}
#find the words throughout the tiles
wordsThroughTile = (grid, x, y) ->
	strings = []
	for length in [MIN_WORD_LENGTH..GRID_SIZE]
		range = length -1
		addTiles = (func) ->
			strings.push (func(i) for i in [0..range]).join ''
		for offset in [0...length]
			# Vertical
			if inRange(x - offset, y) and inRange(x - offset + range, y)
				addTiles (i) -> grid[x - offset + i][y]
			# Horizontal
			if inRange(x, y - offset) and inRange(x, y - offset + range)
				addTiles (i) -> grid[x][y - offset + i]
			# Diagonal (upper left to lower right)
			if inRange(x - offset, y - offset) and
					inRange(x - offset + range, y - offset + range)
				addTiles (i) -> grid[x - offset + i][y - offset + i]
			# Diagonal (lower-left to upper right)
			if inRange(x - offset, y + offset) and
					inRange(x - offset + range, y + offset - range)
				addTiles (i) -> grid[x - offset + i][y + offset - i]
		str for str in strings when isWord str
# error in here somewhere
console.log "Welcome to 5x5!"
for x in [0...GRID_SIZE]
	for y in [0...GRID_SIZE]
		scoreMove grid, {x1: x, x2: x, y1: y, y2: y}
# error above somehere
unless usedWords.length is 0
	console.log """
		Initially used words:
		#{usedWords.join(', ')}
	"""
console.log "Please choose a tile in the form (x,y)."
promptForTile1 = ->
	printGrid()
	console.log "Please enter coordinates for the first tile."
	inputCallback = (input) ->
		try
			{x, y} = strToCoordinates input
		catch e
			console.log e
			return
		promptForTile2 x, y
promptForTile2 = (x1, y1) ->
	console.log "Please enter coordinates for the second tile."
	inputCallback = (input) ->
		try
			{x: x2, y: y2} = strToCoordinates input
		catch e
			console.log e
			return
		if x1 is x2 and y1 is y2
			console.log "The second tile must be different from the first."
		else
			console.log "Swapping (#{x1}, #{y1}) with (#{x2}, #{y2})..."
			x1--; x2--; y1--; y2--; # convert 1 based indices to 0 based
			[grid[x1][y1], grid[x2][y2]] = [grid[x2][y2], grid[x1][y1]]
			{moveScore, newWords} = scoreMove grid, {x2, y1, x2, y2}
			unless moveScore is 0
				console.log """
					you formed the following word(s):
					#{newWords.join(', ')}
				"""
				score += moveScore
			moveCount++
			console.log "Your score after #{moveCount} moves: #{score}"
			promptForTile1()

1st error is "TypeError: number is not a function" with no line number specified.
2nd error is a runtime error: the list of initially used words is "ZZZ," and ", ," a bunch of times.