[Bug] Synthesis from monolingual local models fails

[eginhard]

Describe the bug

Synthesis from monolingual local models fails because of missing config attribute.

To Reproduce

from TTS.api import TTS

cloud = TTS(model_name="tts_models/de/thorsten/vits")  # just to download the model
cloud.tts("test")  # this works fine

from TTS.utils.generic_utils import get_user_data_dir
model = os.path.join(get_user_data_dir("tts"), "tts_models--de--thorsten--vits", "model_file.pth")
config = os.path.join(get_user_data_dir("tts"), "tts_models--de--thorsten--vits", "config.json")
local = TTS(model_path=model, config_path=config)
_ = local.tts("test")

The last line results in the following error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File ".../TTS/api.py", line 357, in tts
    self._check_arguments(
  File ".../TTS/api.py", line 253, in _check_arguments
    if self.is_multi_lingual and language is None:
  File ".../torch/nn/modules/module.py", line 1695, in __getattr__
    raise AttributeError(f"'{type(self).__name__}' object has no attribute '{name}'")
AttributeError: 'TTS' object has no attribute 'is_multi_lingual'

Expected behavior

No response

Logs

No response

Environment

{
    "CUDA": {
        "GPU": [],
        "available": false,
        "version": "12.1"
    },
    "Packages": {
        "PyTorch_debug": false,
        "PyTorch_version": "2.1.1+cu121",
        "TTS": "0.21.3",
        "numpy": "1.22.0"
    },
    "System": {
        "OS": "Linux",
        "architecture": [
            "64bit",
            "ELF"
        ],
        "processor": "x86_64",
        "python": "3.10.11",
        "version": "#38~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Thu Nov  2 18:01:13 UTC 2"
    }
}

Additional context

The error message is somewhat confusing because is_multi_lingual is defined, but one variable used in that property function is None in certain cases. More details: https://github.com/pytorch/pytorch/issues/13981

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[chibiskuld]

This still happening. v0.22.0

self.config.languages is calling in a circular fashion so len(self.config.languages) > 1 on line 102 fails.

the method should be:

    @property
    def is_multi_lingual(self):
        # Not sure what sets this to None, but applied a fix to prevent crashing.
        if hasattr(self.synthesizer.tts_model, "language_manager") and self.synthesizer.tts_model.language_manager:
            return self.synthesizer.tts_model.language_manager.num_languages > 1
        if (
            isinstance(self.model_name, str)
            and "xtts" in self.model_name
            or self.config
            and "xtts" in self.config.model
        ):
            return True
        return False

[eginhard]

It's fixed in our fork: https://github.com/idiap/coqui-ai-TTS