Fix a compil and a Coverity warning

eeschema/sch_io/kicad_sexpr/sch_io_kicad_sexpr.cpp

@@ -524,7 +524,6 @@ void SCH_IO_KICAD_SEXPR::Format( SCH_SELECTION* aSelection, SCH_SHEET_PATH* aSel
     m_schematic = &aSchematic;
     m_out = aFormatter;
 
-    size_t                          i;
     std::map<wxString, LIB_SYMBOL*> libSymbols;
     SCH_SCREEN*                     screen = aSelection->GetScreen();
     std::set<SCH_TABLE*>            promotedTables;

qa/tests/eeschema/test_sch_group.cpp

@@ -55,7 +55,7 @@ public:
 
     void CreateTestSchematic()
     {
-        m_schematic.release();
+        m_schematic.reset();
 
         m_manager.LoadProject( "" );
         m_schematic = std::make_unique<SCHEMATIC>( &m_manager.Prj() );