Revert "[ChannelSelection] Avoid BSoD from some badly coded plugins"

This reverts commit 1f88c91.

I have reverted this as it can be handled in the plugins.

lib/python/Screens/ChannelSelection.py

@@ -2040,12 +2040,7 @@ def __init__(self, session):
 			})
 
 		if type(self) is ChannelSelection:
-			try:
-				assert ChannelSelection.instance is None, "class InfoBar is a singleton class and just one instance of this class is allowed!"
-			except Exception as err:
-				print("%s: '%s'" % (type(err).__name__, err))
-				import traceback
-				traceback.print_exc()
+			assert ChannelSelection.instance is None, "class InfoBar is a singleton class and just one instance of this class is allowed!"
 			ChannelSelection.instance = self
 		self.startServiceRef = None
 		self.history = []