fix: do not fail if description and image is not found for madara

Now, it should not fail if an image thumbnail or the "Summary" section is missing.

Examples:

• https://zetrotranslation.com/novel/my-younger-stepsister-with-whom-i-have-never-spoken-to-is-an-online-friend-from-a-game-into-which-i-have-been-fooling-around-for-years/ (Missing summary)
• https://zetrotranslation.com/novel/i-broke-up-with-my-girlfriend-who-was-cheating-on-me-but-she-was-so-deeply-sorry-that-i-couldnt-help-but-forgive-her/ (Missing thumbnail)