fixed error with trailing zero symbol as placeholder character

code/AssetLib/Collada/ColladaExporter.cpp

@@ -91,7 +91,7 @@ void ExportSceneCollada(const char *pFile, IOSystem *pIOSystem, const aiScene *p
 // Encodes a string into a valid XML ID using the xsd:ID schema qualifications.
 static const std::string XMLIDEncode(const std::string &name) {
     const char XML_ID_CHARS[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_-.";
-    const unsigned int XML_ID_CHARS_COUNT = sizeof(XML_ID_CHARS) / sizeof(char);
+    const unsigned int XML_ID_CHARS_COUNT = sizeof(XML_ID_CHARS) / sizeof(char) - 1;
 
     if (name.length() == 0) {
         return name;