nicely handle exceptions when processing scripts, tell the user about them

Let's help the user by saying what's going on.

lib/msf/base/sessions/scriptable.rb

@@ -164,13 +164,17 @@ module Scriptable
     else
       full_path = self.class.find_script_path(script_name)
 
-      # No path found?  Weak.
       if full_path.nil?
         print_error("The specified script could not be found: #{script_name}")
-        return true
+        return
+      end
+
+      begin
+        execute_file(full_path, args)
+        framework.events.on_session_script_run(self, full_path)
+      rescue StandardError => e
+        print_error("Could not execute #{script_name}: #{e.class} #{e}")
       end
-      framework.events.on_session_script_run(self, full_path)
-      execute_file(full_path, args)
     end
   end