add extra safeties to safe_delete macros

Engine/source/core/util/safeDelete.h

@@ -34,7 +34,7 @@
 /// @param a Object to delete
 /// @see #SAFE_DELETE_ARRAY(), #SAFE_DELETE_OBJECT(), #SAFE_FREE(), #SAFE_FREE_REFERENCE()
 //-----------------------------------------------------------------------------
-#define SAFE_DELETE(a) {delete (a); (a) = NULL; }
+#define SAFE_DELETE(a) {if((a) != NULL) { delete (a); (a) = NULL; } }
 
 #undef  SAFE_DELETE_ARRAY
 
@@ -44,7 +44,7 @@
 /// @param a Array to delete
 /// @see #SAFE_DELETE(), #SAFE_DELETE_OBJECT(), #SAFE_FREE(), #SAFE_FREE_REFERENCE()
 //-----------------------------------------------------------------------------
-#define SAFE_DELETE_ARRAY(a) { delete [] (a); (a) = NULL; }
+#define SAFE_DELETE_ARRAY(a) { if((a) != NULL) { delete [] (a); (a) = NULL; } }
 
 #undef  SAFE_DELETE_OBJECT