accept PNGs that have broken CRC32 checksums for ancillary chunks, which is apparently a thing we need to deal with???

dlibrary/dlibrary.py

@@ -22,7 +22,8 @@ import zipfile
 import dlsite_async
 import fitz
 from libsixel import *
-from PIL import Image
+from PIL import Image, UnidentifiedImageError
+import PIL.ImageFile
 from jinja2 import Environment, PackageLoader, select_autoescape
 import pyuca
 import rarfile
@@ -918,8 +919,17 @@ def descendant_files_ignore(path, exclude):
     return result
 
 def standalone_image_size(filepath):
+    try:
         with Image.open(filepath) as im:
             return im.size
+    except UnidentifiedImageError:
+        print(f'Warning: PIL failed to load image {filepath}! Retrying with less strict settings')
+        PIL.ImageFile.LOAD_TRUNCATED_IMAGES = True
+        try:
+            with Image.open(filepath) as im:
+                return im.size
+        finally:
+            PIL.ImageFile.LOAD_TRUNCATED_IMAGES = False
 
 def pdf_image_sizes(filepath):
     sizes_by_xref = {}