Confusing error message when jubaclassifier get invalid configuration file

[unnonouno]

When a user misspelled "parameter" in jubaclassifier configuration, jubaclassifier returns this error.

Dynamic exception type: jubatus::jsonconfig::type_error::what: Object is expected, but Null is given. ()

This error mislead the user because path information is empty.

The reason of this phenomena is a little complicated.
The server can correctly read this configuration since parameter field in classifier_serv_config is optional.
https://github.com/jubatus/jubatus/blob/master/src/server/classifier_serv.cpp#L57
When a user misspelled it, the value of parameter is null and param variable is empty.
https://github.com/jubatus/jubatus/blob/master/src/server/classifier_serv.cpp#L110
So, the factory of classifier throws type_error with an empty path.
https://github.com/jubatus/jubatus/blob/master/src/classifier/classifier_factory.cpp#L46

I have two method to correct it.

1. Change parameter field mandatory.
2. Set default path to param local variable like this.

jsonconfig::config param(json(), ".parameter");  

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

Closing this issue after a prolonged period of inactivity. Please feel free to create a new issue or re-open it if you need.