def interpret_existing_path_env(value: str, field_name: str) -> ExistingPath:
    """Interpret a path environment variable value as an existing path.

    Args:
        value: The environment variable value.
        field_name: The field name.

    Returns:
        The interpreted value.

    Raises:
        EnvironmentVarValueError: If the path does not exist.
    """
    path = Path(value)
    if not path.exists():
        msg = f"Path does not exist: {path} for {field_name}"
        raise EnvironmentVarValueError(msg)
    return path
Interpret a path environment variable value as an existing path.

    Args:
        value: The environment variable value.
        field_name: The field name.

    Returns:
        The interpreted value.

    Raises:
        EnvironmentVarValueError: If the path does not exist.
    
reflex/environment.py