`TypeError` while using `rot-10` decoding

[dhondta]

$ echo "sclvk" | codext decode rot-10
isbla

$ echo "sclvkv" | codext decode rot-10
Traceback (most recent call last):
  File "/home/morfal/.local/bin/codext", line 8, in <module>
    sys.exit(main())
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__init__.py", line 254, in main
    raise e
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__init__.py", line 222, in main
    c = getattr(codecs, ["encode", "decode"][args.command == "decode"])(c, encoding, args.errors)
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__common__.py", line 905, in decode
    return lookup(encoding).decode(obj, errors)[0]
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__common__.py", line 306, in decode
    return fdec(input, errors)
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__common__.py", line 824, in _wrapper
    r = f(a0, *args[1:], **kwargs)
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/crypto/rot.py", line 76, in decode
    r = _rotn(t, -47, [ROT47]) if i == 47 else _rotn(t, -i)
TypeError: bad operand type for unary -: 'str'

$ echo "sclvkm" | codext decode rot-10
isblac

$ echo "sclvkp" | codext decode rot-10
Traceback (most recent call last):
  File "/home/morfal/.local/bin/codext", line 8, in <module>
    sys.exit(main())
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__init__.py", line 254, in main
    raise e
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__init__.py", line 222, in main
    c = getattr(codecs, ["encode", "decode"][args.command == "decode"])(c, encoding, args.errors)
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__common__.py", line 905, in decode
    return lookup(encoding).decode(obj, errors)[0]
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__common__.py", line 306, in decode
    return fdec(input, errors)
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/__common__.py", line 824, in _wrapper
    r = f(a0, *args[1:], **kwargs)
  File "/home/morfal/.local/lib/python3.10/site-packages/codext/crypto/rot.py", line 76, in decode
    r = _rotn(t, -47, [ROT47]) if i == 47 else _rotn(t, -i)
TypeError: bad operand type for unary -: 'str'
``