Unsafe Image getter

[GermanHydrogen]

A log of image processors got duplicate code similar to

if image.catalog is None:
    log.warning("No catalog in image.")
    return image

This could be fixed if image had unsafe getter for the main properties like

class Image:
    [...]
    def get_data_unsafe(self) -> np.ndarray:
        if self.data is None:
            raise exc.ImageError("Image has not data.")
        return image.data

Another possibilities would be to change the default getter to the unsafe option and introducing a safe getter which return optionals.