Mixer: Fix redundant operations in strip removal.

mixer/src/Mixer_Strip.C

@@ -1242,7 +1242,6 @@ Mixer_Strip::command_move_right ( void )
 void
 Mixer_Strip::command_close ( void )
 {
-    mixer->remove( this );
     Fl::delete_widget( this );
 }
 

nonlib/JACK/Port.C

@@ -335,6 +335,8 @@ namespace JACK
     const char **
     Port::connections ( void )
     {
+        ASSERT( _port, "Attempt to get connections of null port" );
+
         return jack_port_get_connections( _port );
     }