What causes "invalid argument type %s" in wavetermdev/waveterm?

Remove the unsupported parameter type from the service method signature.

invalid argument type %s

Error message

invalid argument type %s

What it means

Thrown by convertArgument's default branch when a service method parameter's reflect.Kind is one the RPC bridge does not support at all (anything outside String, Bool, numeric, Map, Slice, Struct, Ptr, and special wave arg types) — e.g. channels, funcs, interfaces, complex numbers, or unsafe pointers.

Source

Thrown at pkg/service/service.go:262

		return convertComplex(argType, jsonArg)

	case reflect.Struct:
		if jsonType.Kind() != reflect.Map {
			return nil, fmt.Errorf("cannot convert %T to %s", jsonArg, argType)
		}
		return convertComplex(argType, jsonArg)

	case reflect.Ptr:
		if argType.Elem().Kind() != reflect.Struct {
			return nil, fmt.Errorf("invalid pointer type %s", argType)
		}
		if jsonType.Kind() != reflect.Map {
			return nil, fmt.Errorf("cannot convert %T to %s", jsonArg, argType)
		}
		return convertComplex(argType, jsonArg)

	default:
		return nil, fmt.Errorf("invalid argument type %s", argType)
	}
}

func isNilable(val reflect.Value) bool {
	switch val.Kind() {
	case reflect.Ptr, reflect.Slice, reflect.Map, reflect.Interface, reflect.Chan, reflect.Func:
		return true
	}
	return false

}

func convertReturnValues(rtnVals []reflect.Value) *WebReturnType {
	rtn := &WebReturnType{}
	if len(rtnVals) == 0 {
		return rtn
	}
	for _, val := range rtnVals {

View on GitHub (pinned to a4447c1563)

Solutions

Remove the unsupported parameter type from the service method signature.
Replace func/chan params with event subscriptions or ids usable with the pubsub system.
For dynamic payloads, use a supported type such as map[string]any or a struct instead of interface{}.
If the type is actually a Wave special type (WaveObj etc.), make it match isSpecialWaveArgType's recognized types so it routes through convertSpecial.

Example fix

// before
func (s *Svc) Watch(ch chan int) error

// after
func (s *Svc) Watch(scope string) error { // subscribe via WPS events
    ...
}

Defensive patterns

Strategy: validation

Validate before calling

// audit the Go signature: supported kinds are string,bool,numbers,map,slice,struct,*struct + special wave types
const supported = new Set(['string','bool','number','object','array']);
if (!supported.has(typeof arg)) throw new Error('arg type unsupported by RPC bridge');

Try / catch

try {
  const rtn = await callService(svc, method, args);
  if (rtn.error?.includes('invalid argument type')) throw new Error('method signature has an unsupported parameter kind');
} catch (e) { /* the method itself must be redesigned; no client-side fix */ }

Prevention

Never expose chan/func/interface{} parameters on RPC services.
Use map[string]any or structs for dynamic payloads.
Add a registration-time check that walks each service method's parameter kinds.

When it happens

Trigger: Calling a service method whose signature includes a chan, func, interface{}, complex, or other exotic parameter type; the error fires on any call attempt regardless of the JSON value passed.

Common situations: Adding a callback or channel parameter to an existing service method and exposing it over RPC; using interface{} parameters assuming the bridge passes raw JSON through.

Related errors

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/4321ac9c12b0c691. Report an issue: GitHub.