`scan': invalid byte sequence in UTF-8 (ArgumentError)

I'm trying to read a .txt file in ruby and split the text line-by-line.

Here is my code:

def file_read(filename)
  File.open(filename, 'r').read
end

puts f = file_read('alice_in_wonderland.txt')

This works perfectly. But when I add the method line_cutter like this:

def file_read(filename)
  File.open(filename, 'r').read
end

def line_cutter(file)
  file.scan(/\w/)
end

puts f = line_cutter(file_read('alice_in_wonderland.txt'))

I get an error:

`scan': invalid byte sequence in UTF-8 (ArgumentError)

I found this online for untrusted website and tried to use it for my own code but it's not working. How can I remove this error?

Link to the file: File