Update GetImageBlob/GetImagesBlob to return blob when ExceptionInfo i…

[kfxhjz]

…s warning kind

[justinfx]

I didn't realize MagickGetImageBlob could report warnings. Are we just leaving that up to the caller to determine if the error is a warning?

[kfxhjz]

Yes，So we need return blob data first.

outImgBlob, err := mw.GetImagesBlob()
if err != nil {
	// return res, fmt.Errorf("GetImagesBlob fail: %w", err)
	
	var exInfo *imagick.ExceptionInfo
	if errors.As(err, &exInfo) && exInfo.IsErrorKind() {
		return res, fmt.Errorf("GetImagesBlob fail: %w", err)
	}
	log.Warn().Err(err).Msg("GetImagesBlob fail")
}