Unable to tokenize sentences that start with at mark

[cromz22]

Tokenization fails when a sentence starts with "@".
This doesn't seem to be an issue when jumanpp is called through subprocess or rhoknp.

To reproduce:

import subprocess
from pyknp import Juman
import rhoknp


def subprocess_tokenize(ja_sent):
    command = f"echo {ja_sent} | jumanpp --segment"
    return subprocess.run(command, shell=True, capture_output=True, text=True).stdout.strip()


def pyknp_tokenize(ja_sent):
    jumanpp = Juman()
    return " ".join([mrph.midasi for mrph in jumanpp.analysis(ja_sent).mrph_list()])


def rhoknp_tokenize(ja_sent):
    jumanpp = rhoknp.Jumanpp()
    return " ".join([str(morph) for morph in jumanpp.apply(ja_sent).morphemes])


def main():
    ja_sent = "@@抄録@@移動アドホックネットワークのための適応経路チューニングスキーム「OR2」を提案した。"
    ja_sent = "@ECOVISIONの導入効果は以下の通りである。"

    ja_sent = pyknp_tokenize(ja_sent)
    print(ja_sent)


if __name__ == "__main__":
    main()

Standard error:

Traceback (most recent call last):
  File "error.py", line 30, in <module>
    main()
  File "error.py", line 25, in main
    ja_sent = pyknp_tokenize(ja_sent)
  File "error.py", line 13, in pyknp_tokenize
    return " ".join([mrph.midasi for mrph in jumanpp.analysis(ja_sent).mrph_list()])
  File "/path_to_venv/lib/python3.8/site-packages/pyknp/juman/juman.py", line 98, in analysis
    return self.juman(input_str, juman_format)
  File "/path_to_venv/venv/lib/python3.8/site-packages/pyknp/juman/juman.py", line 85, in juman
    result = MList(self.juman_lines(input_str), juman_format)
  File "/path_to_venv/venv/lib/python3.8/site-packages/pyknp/juman/mlist.py", line 26, in __init__
    self._mrph[-1].push_doukei(Morpheme(line[2:], mid, juman_format))
IndexError: list index out of range