fix: crash when a sink input was removed

src/mixer.rs

@@ -238,12 +238,9 @@ impl Mixer {
                             Some(current_index) => {
                                 drop(selected_index_lock);
 
-                                let removed_sink_input_index = self
-                                    .sink_inputs
-                                    .keys()
-                                    .position(|k| *k == sink_index)
-                                    .unwrap();
-
+                                if let Some(removed_sink_input_index) =
+                                    self.sink_inputs.keys().position(|k| *k == sink_index)
+                                {
                                     let current_key =
                                         *self.sink_inputs.keys().nth(current_index).unwrap();
 
@@ -255,6 +252,7 @@ impl Mixer {
                                         }
                                     }
                                 }
+                            }
 
                             None => (),
                         }