Update python_easy_chess_gui.py

* Don't crash the program when there are no engine file in Engines folder. Inform the user to install the engine first when user goes for play mode. This would also solve issue in Linux if there are no linux engine in Engine folder.

Author: fsmosca

python_easy_chess_gui.py

@@ -60,7 +60,7 @@
 
 
 APP_NAME = 'Python Easy Chess GUI'
-APP_VERSION = 'v1.5'
+APP_VERSION = 'v1.6'
 BOX_TITLE = '{} {}'.format(APP_NAME, APP_VERSION)
 
 
@@ -2496,6 +2496,7 @@ def main_loop(self):
 
         :return:
         """
+        engine_id_name = None
         layout = self.build_main_layout(True)
 
         # Use white layout as default window
@@ -2511,16 +2512,26 @@ def main_loop(self):
         self.engine_id_name_list = self.get_engine_id_name_list()
 
         # Define default opponent engine, user can change this later.
-        engine_id_name = self.opp_id_name = self.engine_id_name_list[0]
-        self.opp_file, self.opp_path_and_file = self.get_engine_file(
-            engine_id_name)
+        try:
+            engine_id_name = self.opp_id_name = self.engine_id_name_list[0]
+            self.opp_file, self.opp_path_and_file = self.get_engine_file(
+                engine_id_name)
+        except IndexError as e:
+            logging.warning(e)
+        except Exception:
+            logging.exception('Error in getting opponent engine!')
 
         # Define default adviser engine, user can change this later.
-        self.adviser_id_name = self.engine_id_name_list[1] \
-               if len(self.engine_id_name_list) >= 2 \
-               else self.engine_id_name_list[0]
-        self.adviser_file, self.adviser_path_and_file = self.get_engine_file(
-            self.adviser_id_name)
+        try:
+            self.adviser_id_name = self.engine_id_name_list[1] \
+                   if len(self.engine_id_name_list) >= 2 \
+                   else self.engine_id_name_list[0]
+            self.adviser_file, self.adviser_path_and_file = self.get_engine_file(
+                self.adviser_id_name)
+        except IndexError as e:
+            logging.warning(e)
+        except Exception:
+            logging.exception('Error in getting adviser engine!')
 
         self.init_game()
 
@@ -3434,6 +3445,12 @@ def main_loop(self):
 
             # Mode: Neutral
             if button == 'Play':
+                if engine_id_name is None:
+                    logging.warning('Install engine first!')
+                    sg.Popup('Install engine first! in Engine/Manage/Install',
+                             icon='Icon/pecg.ico', title='Mode')
+                    continue
+                    
                 # Change menu from Neutral to Play
                 self.menu_elem.Update(menu_def_play)
                 self.psg_board = copy.deepcopy(initial_board)