add assertion

tinyxml2.cpp

@@ -2327,6 +2327,7 @@ void XMLDocument::SetError( XMLError error, int lineNum, const char* format, ...
     size_t BUFFER_SIZE = 1000;
     char* buffer = new char[BUFFER_SIZE];
 
+    TIXMLASSERT(sizeof(error) <= sizeof(int));
     TIXML_SNPRINTF(buffer, BUFFER_SIZE, "Error=%s ErrorID=%d (0x%x) Line number=%d", ErrorIDToName(error), int(error), int(error), lineNum);
 
 	if (format) {