fixed None extraction bug

Author: cansik

README.md

@@ -11,7 +11,7 @@ Further ideas can be implemented, for example a sobel based method is already av
 To install the package use the following pip command:
 
 ```
-pip install git+https://github.com/cansik/sharp-frame-extractor.git@1.6.2
+pip install git+https://github.com/cansik/sharp-frame-extractor.git@1.6.3
 ```
 
 ### Usage

setup.py

@@ -6,7 +6,7 @@
 
 setup(
     name=NAME,
-    version='1.6.2',
+    version='1.6.3',
     packages=required_packages,
     url='https://github.com/cansik/sharp-frame-extractor',
     license='MIT License',

sharp_frame_extractor/SharpFrameExtractor.py

@@ -89,6 +89,8 @@ def extract(self, video_file, output_path, window_size_ms, target_frame_count: i
                              self.min_sharpness,
                              buffer_size),)) as pool:
             for res in tqdm.tqdm(pool.imap_unordered(extract, windows), total=len(windows), desc="frame extraction"):
+                if res is None:
+                    continue
                 name, sharpness = res
                 results.append(name)