Fix for #1718 (fetch of metadata from google without cover leads to exception)

cps/editbooks.py

@@ -652,6 +652,9 @@ def edit_book(book_id):
                 if to_save["cover_url"]:
                     if not current_user.role_upload():
                         return "", (403)
+                    if to_save["cover_url"].endswith('/static/generic_cover.jpg'):
+                        book.has_cover = 0
+                    else:
                         result, error = helper.save_cover_from_url(to_save["cover_url"], book.path)
                         if result is True:
                             book.has_cover = 1

cps/static/js/get_meta.js

@@ -108,7 +108,7 @@ $(function () {
                         tags: result.volumeInfo.categories || [],
                         rating: result.volumeInfo.averageRating || 0,
                         cover: result.volumeInfo.imageLinks ?
-                            result.volumeInfo.imageLinks.thumbnail : "/static/generic_cover.jpg",
+                            result.volumeInfo.imageLinks.thumbnail : location + "/../../../static/generic_cover.jpg",
                         url: "https://books.google.com/books?id=" + result.id,
                         source: {
                             id: "google",