Failed to generate types when schemas are not in a reticular structure

[C-ra-ZY]

Describe the bug
If there are no $ref in schemas, current code would skip the procedure of generating types, whereas the other outputs are normal, like schemas and endpoint.
Although is not a common demand, spliting types info into a single file would take effect on decoupling and customization.

Minimal reproduction
please see this page

Expected behavior
the output should contain types information anyway like:

type DemoInformation = {
  issuedTo: string;
  token: string;
  expirationDate: string;
  group: string;
  identityId: string;
};

Additional context
I have drafted fix.