IndentationError: unindent does not match any outer indentation level, how to fix?

Question

Python

I'm writing a discord bot in Python.
I made a command that connects to the Tcp - Server on port 2000.

@client.command(pass_context = True)
async def airdrop(ctx):
  sock.connect(("127.0.0.1", 2000))
  sock.send(air_bytes)
  time.sleep(1.5)
  #sock.close()
  await ctx.send('Test Airdrop was sent')

Everything seems to be working, but when adding the sock.close() method, an error pops up:

File "bot.py", line 49
    sock.close()
               ^
IndentationError: unindent does not match any outer indentation level

What is the problem and how can it be solved?