fixed temp directory cleaning problem on exit

src/upscaler.py

@@ -4,7 +4,7 @@
 Name: Video2X Upscaler
 Author: K4YT3X
 Date Created: December 10, 2018
-Last Modified: October 6, 2019
+Last Modified: December 11, 2019
 
 Dev: SAT3LL
 
@@ -82,7 +82,7 @@ class Upscaler:
         """delete temp directories when done
         """
         if not self.preserve_frames:
-            for directory in [self.extracted_frames, self.upscaled_frames]:
+            for directory in [self.extracted_frames, self.upscaled_frames, self.video2x_cache_directory]:
                 try:
                     # avalon framework cannot be used if python is shutting down
                     # therefore, plain print is used

src/video2x.py

@@ -13,7 +13,7 @@ __      __  _       _                  ___   __   __
 Name: Video2X Controller
 Creator: K4YT3X
 Date Created: Feb 24, 2018
-Last Modified: November 15, 2019
+Last Modified: December 11, 2019
 
 Editor: BrianPetkovsek
 Editor: SAT3LL
@@ -438,6 +438,10 @@ except Exception:
     Avalon.error('An exception has occurred')
     traceback.print_exc()
 
+    # try cleaning up temp directories
+    with contextlib.suppress(Exception):
+        upscaler.cleanup_temp_directories()
+
 finally:
     # remove Video2X cache directory
     with contextlib.suppress(FileNotFoundError):

src/video2x_gui.py

@@ -18,6 +18,7 @@ from tkinter import *
 from tkinter import messagebox
 from tkinter import ttk
 from tkinter.filedialog import *
+import contextlib
 import pathlib
 import sys
 import tempfile
@@ -204,7 +205,7 @@ class Video2xGui():
 
         # preserve frames
         self.preserve_frames = BooleanVar(self.options_left)
-        self.preserve_frames.set(True)
+        self.preserve_frames.set(False)
         Label(self.options_right, text='Preserve Frames', relief=RIDGE, width=15).grid(row=3, column=0, padx=2, pady=3)
         preserve_frames_menu = OptionMenu(self.options_right, self.preserve_frames, *{True, False})
         preserve_frames_menu.grid(row=3, column=1, padx=2, pady=3, sticky=W)
@@ -267,6 +268,7 @@ class Video2xGui():
 
     def _upscale(self):
 
+        try:
             # start timer
             begin_time = time.time()
 
@@ -357,6 +359,14 @@ class Video2xGui():
             self.running = False
             self.start_button_text.set('Start')
         
+        except Exception as e:
+            messagebox.showerror('Error', f'Upscaler ran into an error:\n{e}')
+
+            # try cleaning up temp directories
+            with contextlib.suppress(Exception):
+                self.upscaler.cleanup_temp_directories()
+
+
     def _progress_bar(self):
         """ This method prints a progress bar