CBORStream2Deserializer: Fix out of memory write

frame_serialize/CBORStream2Deserializer.cpp

@@ -15,7 +15,7 @@ namespace {
         std::vector<char> s(16384);
         size_t len = s.size() - 1;
         cborErr(cbor_value_copy_text_string(&value, s.data(), &len, nullptr));
-        s[len + 1] = 0;
+        s[len] = 0;
         cborErr(cbor_value_advance(&value));
         return {s.data()};
     }