Fix circular buffer index

Index was previously not being increased as statement could not be reached

Firmware/src/Util/CircularBuffer.h

@@ -10,8 +10,8 @@ public:
   /// @brief Warning: Does not deconstruct entry! If necessary use
   /// etl::circular_buffer instead!
   T &pop() {
-    return buffer[index];
     index = (index + 1) % buffer.size();
+    return buffer[index];
   }
 
 private: