Fixing regression around thumbnails for image sequences and missing f…

…iles. Adding a new "NotFound" thumbnail image as a placeholder.

src/classes/thumbnail.py

@@ -30,6 +30,7 @@
 import openshot
 import socket
 import time
+import shutil
 from requests import get
 from threading import Thread
 from classes import info
@@ -74,13 +75,17 @@ def GetThumbPath(file_id, thumbnail_frame, clear_cache=False):
 
 def GenerateThumbnail(file_path, thumb_path, thumbnail_frame, width, height, mask, overlay):
     """Create thumbnail image, and check for rotate metadata (if any)"""
-    if not os.path.exists(file_path):
-        log.warning(f"Cannot generate thumbnail for missing file: {file_path}")
+    # Create a clip object and get the reader
+    try:
+        clip = openshot.Clip(file_path)
+        reader = clip.Reader()
+    except RuntimeError as ex:
+        # Any failure calling Reader (i.e. file missing or corrupt) use placeholder thumbnail
+        not_found_path = os.path.join(info.IMAGES_PATH, "NotFound@2x.png")
+        shutil.copyfile(not_found_path, thumb_path)
+        log.warning(f"Failed to generate thumbnail for missing file: {file_path}")
         return
 
-    # Create a clip object and get the reader
-    clip = openshot.Clip(file_path)
-    reader = clip.Reader()
     scale = get_app().devicePixelRatio()
 
     if scale > 1.0:

src/windows/preview_thread.py

@@ -311,9 +311,6 @@ def LoadFile(self, path=None):
         # Check to see if this path is already loaded
         if path == self.clip_path or (not path and not self.clip_path):
             return
-        if path and not os.path.exists(path):
-            log.warning(f"Cannot load missing file for preview: {path}")
-            return
 
         log.info("LoadFile %s" % path)