Use remote_id resolver to load books, user

bookwyrm/activitypub/book.py

@@ -12,13 +12,13 @@ class Book(ActivityObject):
     sortTitle: str = ''
     subtitle: str = ''
     description: str = ''
-    languages: List[str]
+    languages: List[str] = field(default_factory=lambda: [])
     series: str = ''
     seriesNumber: str = ''
-    subjects: List[str]
-    subjectPlaces: List[str]
+    subjects: List[str] = field(default_factory=lambda: [])
+    subjectPlaces: List[str] = field(default_factory=lambda: [])
 
-    authors: List[str]
+    authors: List[str] = field(default_factory=lambda: [])
     firstPublishedDate: str = ''
     publishedDate: str = ''
 
@@ -33,22 +33,22 @@ class Book(ActivityObject):
 @dataclass(init=False)
 class Edition(Book):
     ''' Edition instance of a book object '''
-    isbn10: str
-    isbn13: str
-    oclcNumber: str
-    asin: str
-    pages: str
-    physicalFormat: str
-    publishers: List[str]
-
     work: str
+    isbn10: str = ''
+    isbn13: str = ''
+    oclcNumber: str = ''
+    asin: str = ''
+    pages: str = ''
+    physicalFormat: str = ''
+    publishers: List[str] = field(default_factory=lambda: [])
+
     type: str = 'Edition'
 
 
 @dataclass(init=False)
 class Work(Book):
     ''' work instance of a book object '''
-    lccn: str
+    lccn: str = ''
     editions: List[str]
     type: str = 'Work'