Just to add some info.
I'm trying now the same app inside RhoElements v126.96.36.199 and I've seen that the culprit seems an openDatabase call:
this._db = openDatabase('xtel.sm1', '1.0', 'xtel.sm1', 20000000);
can be a problem with the name of the database? (no, I can't change it on the fly to test )
Final bit of info.
At the end it was not a problem of the name of the database.
The problem was the requested size for the database. Changing in the config.xml accordingly to the request in the code solved the issue (from the original 5MB to 25MB).
The warning in the log was probably not one of the clearest, but with version 2 of RhoElements at least it reported the corrected line where the issue was found instead of the "line 0" reported by version 1.
Hope this helps others that sometimes needs to test other people code.
Thanks for sharing Pietro.