Error 'missing field "folder"' for existing transports

[nicodh]

Since existing transports have no field "folder" which was introduced in 942172a listing or loading existing transports cause an error when being deserialized

Maybe we should a default value in

core/src/login_param.rs

Line 73 in f20907d

pub folder: String,

[link2xt]

Probably just need a #[serde(default)] on top of it, so it will deserialize to empty string.