[BUG]: G2P module fails to initialize when using `pypinyin` as backend

[yuantuo666]

Describe the bug

The G2P module fails to initialize due to using an unassigned variable.

How To Reproduce

Steps to reproduce the behavior:

1. Config/File changes: using valle model and editing phone_extractor to pypinyin
2. Run command: sh egs/tts/VALLE/run.sh --stage 1
3. See error:

   Traceback (most recent call last):
   File "/app/bins/tts/preprocess.py", line 244, in <module>
   main()
   File "/app/bins/tts/preprocess.py", line 240, in main
   preprocess(cfg, args)
   File "/app/bins/tts/preprocess.py", line 226, in preprocess
   extract_phonme_sequences(dataset, output_path, cfg, dataset_types)
   File "/app/bins/tts/preprocess.py", line 91, in extract_phonme_sequences
   phone_extractor.extract_utt_phone_sequence(cfg, metadata)
   File "/app/processors/phone_extractor.py", line 114, in extract_utt_phone_sequence
   phone_extractor = phoneExtractor(cfg, dataset_name)
   File "/app/processors/phone_extractor.py", line 44, in __init__
   self.g2p_module = G2PModule(backend=cfg.preprocess.phone_extractor)
   File "/app/text/g2p_module.py", line 113, in __init__
   self.backend = self._initialize_backend(
   File "/app/text/g2p_module.py", line 150, in _initialize_backend
   punctuation_marks=punctuation_marks + self.separator.word,
   AttributeError: 'G2PModule' object has no attribute 'separator'

Expected behavior

The error should not occur.

Additional context

https://github.com/open-mmlab/Amphion/blob/main/text/g2p_module.py

class G2PModule:
    """Phonemize Text."""

    # We support espeak to extract IPA (International Phonetic Alphabet), which supports 100 languages,
    # https://github.com/espeak-ng/espeak-ng/blob/master/docs/languages.md

    def __init__(
        self,
        language="en-us",
        backend="espeak",
        separator=Separator(word="_", syllable="-", phone="|"),
        preserve_punctuation=True,
        punctuation_marks: Union[str, Pattern] = Punctuation.default_marks(),
        with_stress: bool = False,
        tie: Union[bool, str] = False,
        language_switch: LanguageSwitch = "keep-flags",
        words_mismatch: WordMismatch = "ignore",
    ) -> None:
        self.backend = self._initialize_backend(
            backend,
            language,
            punctuation_marks,
            preserve_punctuation,
            with_stress,
            tie,
            language_switch,
            words_mismatch,
        )
        self.separator = separator # variable self.separator is assigned after calling _initialize_backend()

    def _initialize_backend(
        self,
        backend,
        language,
        punctuation_marks,
        preserve_punctuation,
        with_stress,
        tie,
        language_switch,
        words_mismatch,
    ):
        if backend == "espeak":
            return EspeakBackend(
                language,
                punctuation_marks=punctuation_marks,
                preserve_punctuation=preserve_punctuation,
                with_stress=with_stress,
                tie=tie,
                language_switch=language_switch,
                words_mismatch=words_mismatch,
            )
        elif backend in ["pypinyin", "pypinyin_initials_finals"]:
            if language != "cmn":
                raise ValueError(
                    f"{language} is not supported for pypinyin and pypinyin_initials_finals."
                )
            return PypinyinBackend(
                backend=backend,
                punctuation_marks=punctuation_marks + self.separator.word, # variable self.separator is used here before assign
            )
        else:
            raise NotImplementedError(f"{backend}")

Variable self.separator is used in _initialize_backend() before assigned in init()

Possible Solution

Move self.separator = separator in front of self.backend = self._initialize_backend(...)