Circular reference in OpenAPI schema causes stack overflow error

[davbrito]

Problem

When using a circular reference in the OpenAPI schema, the application fails with a stack overflow error.

Details

• Creating a schema with self-referencing models (such as a Todo class containing a collection of Todo as children) triggers a Maximum call stack size exceeded error.
• The stack trace points to an issue in the massimo-cli's get-type.js when processing the circular reference.

Steps to Reproduce

1. Define a model with a circular reference:
2. Generate the OpenAPI schema and attempt to use it with massimo-cli.
3. Observe the error (see image below).

Error Output

Example Model

public class Todo
{
    public int Id { get; set; }
    public string? Name { get; set; }
    public bool IsComplete { get; set; }
    public ICollection<Todo>? Children { get; set; }
}

Example Schema

{
  ...
  "components": {
    "schemas": {
      "Todo": {
        "type": "object",
        "additionalProperties": false,
        "properties": {
          "id": {
            "type": "integer",
            "format": "int32"
          },
          "name": {
            "type": "string",
            "nullable": true
          },
          "isComplete": {
            "type": "boolean"
          },
          "nestedTodos": {
            "type": "array",
            "nullable": true,
            "items": {
              "$ref": "#/components/schemas/Todo"
            }
          }
        }
      }
    }
  }
}

Expected Behavior

The tool should handle circular references gracefully without crashing or exceeding the call stack size.

Actual Behavior

• Throws a Maximum call stack size exceeded error.
• Fails to process the OpenAPI schema with circular references.

Environment

• massimo-cli@0.4.0
• Node.js v22.19.0

Additional Notes

• This issue appears to be related to circular reference handling in the OpenAPI schema parser/processor.
• Other libraries, such as openapi-typescript, are able to handle circular references in OpenAPI schemas successfully. Investigating their approach might provide insights for resolving this issue.