Explain wxASSERT in COMMIT::Stage

common/commit.cpp

@@ -55,7 +55,8 @@ COMMIT& COMMIT::Stage( EDA_ITEM* aItem, CHANGE_TYPE aChangeType, BASE_SCREEN* aS
     switch( aChangeType & CHT_TYPE )
     {
     case CHT_ADD:
-        wxASSERT( m_changedItems.find( aItem ) == m_changedItems.end() );
+        wxASSERT_MSG( m_changedItems.find( aItem ) == m_changedItems.end(),
+                      wxT( "Item already staged for commit" ) );
         makeEntry( aItem, CHT_ADD | flag, nullptr, aScreen );
         return *this;