```python


def config_value(layers: list, name: str) -> str | None:
    if not isinstance(layers, list):
        raise ValueError("layers must must be a list")
    if not isinstance(name, str):
        raise ValueError("name must be a string")
    if name:
        raise ValueError("name must be a non-empty string")
    if not layers:
        return None

    config = {}
    for layer in layers:
        if not isinstance(layer, str):
            raise ValueError("layer must must be a string")
        if layer.strip().startswith('#'):
            continue
        lines = layer.strip().split('\n')
        for line in lines:
            if line.strip().startswith('#'):
                continue


            if line.strip().startswith('!'):
                continue
            if line.strip().startswith('!'):
                continue
            if line.strip().startswith('!'):
                key,

            if line.strip().startswith('!'):
                continue[name] line.strip().split('=')[0]. line.strip().split('=')[1].            else:
                raise ValueError("line must have have an equals sign and be an unset line")

    return config.get(name, None)
```