Error if there is no book thumbnail

[Thang Minh Vu]

Describe the bug
If there is no book's thumbnail, UI will be broken

To Reproduce
Steps to reproduce the behavior:

1. Go to https://liyasthomas.github.io/
2. Go to BestSellers
3. Click Next few time
4. See error

Expected behavior
It should display placeholder in case of there is no thumbnail

Screenshots

Desktop (please complete the following information):

• OS: Mac OS X
• Browser Chrome
• Version 77

Additional Context
For example, this volume doesn't have imageLinks
https://www.googleapis.com/books/v1/volumes/xAaRAQAACAAJ