Investigate whether the `if bitmap is not None` is necessary about pypdfium2 HOT 4 CLOSED

tests/test_basics.py:8: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
prodigy_pdf/__init__.py:27: in generate_pdf_pages
    "image": page_to_image(page),
prodigy_pdf/__init__.py:13: in page_to_image
    pil_image = page.render().to_pil()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <PdfBitmap uuid:5129eced>

    def to_pil(self):
        """
        Convert the bitmap to a :mod:`PIL` image, using :func:`PIL.Image.frombuffer`.
    
        For ``RGBA``, ``RGBX`` and ``L`` buffers, PIL is supposed to share memory with
        the original bitmap buffer, so changes to the buffer should be reflected in the image, and vice versa.
        Otherwise, PIL will make a copy of the data.
    
        Returns:
            PIL.Image.Image: PIL image (representation or copy of the bitmap buffer).
    
        .. versionchanged:: 4.16 Set ``image.readonly = False`` so that changes to the image are also reflected in the buffer.
        """
    
        # https://pillow.readthedocs.io/en/stable/reference/Image.html#PIL.Image.frombuffer
        # https://pillow.readthedocs.io/en/stable/handbook/writing-your-own-image-plugin.html#the-raw-decoder
    
        dest_mode = pdfium_i.BitmapTypeToStrReverse[self.format]
>       image = PIL.Image.frombuffer(
            dest_mode,                  # target color format
            (self.width, self.height),  # size
            self.buffer,                # buffer
            "raw",                      # decoder
            self.mode,                  # input color format
            self.stride,                # bytes per line
            1,                          # orientation (top->bottom)
        )
E       AttributeError: 'NoneType' object has no attribute 'Image'