Update TryExcept(msg='...')` (#9261)

utils/__init__.py

@@ -9,7 +9,7 @@ import threading
 
 class TryExcept(contextlib.ContextDecorator):
     # YOLOv5 TryExcept class. Usage: @TryExcept() decorator or 'with TryExcept():' context manager
-    def __init__(self, msg='default message here'):
+    def __init__(self, msg=''):
         self.msg = msg
 
     def __enter__(self):
@@ -17,7 +17,7 @@ class TryExcept(contextlib.ContextDecorator):
 
     def __exit__(self, exc_type, value, traceback):
         if value:
-            print(f'{self.msg}: {value}')
+            print(f'{self.msg}{value}')
         return True