Jguer/yay · error

expected boolean, got

Error message

expected boolean, got %s

What it means

assign maps a Lua value onto a reflect.Bool struct field and requires an LBool. Other Lua types cannot be interpreted as a Go bool, so it returns an error naming the actual Lua type. The wrapping layer prefixes it with yay.opt.<key>.

Solutions

1. Use Lua's real booleans in init.lua: true or false, unquoted
2. If you need conditional logic, compute the boolean in Lua: yay.opt.rebuild = (os.getenv("CI") ~= nil)
3. Confirm the Go field is bool; if the setting is genuinely tri-state/string, change the struct field type

Example fix

// before (init.lua)
yay.opt.rebuild = "yes"
// after
yay.opt.rebuild = true

-- init.lua
assert(type(yay.opt.rebuild) == "boolean", "yay.opt.rebuild must be true or false")

if err != nil && strings.Contains(err.Error(), "expected boolean") {
    fixBoolOptionInInitLua()
}

When it happens

Trigger: An init.lua option bound to a Go bool field is set to a string or number, e.g. yay.opt.rebuild = "yes" or yay.opt.rebuild = 1.

Common situations: Using strings 'true'/'yes' for booleans (a YAML/JSON habit); using 0/1 numeric flags; Lua expression evaluating to nil instead of a boolean.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• yay.opt.
• expected string, got
• expected number, got
• expected table, got
• entry keys must be strings, got

AI-assisted analysis of Jguer/yay@328f4b4939 (2026-09-07). Data as JSON: /api/errors/472a777346e8a5fc. Report an issue: GitHub.

Appendix: source

Thrown at pkg/settings/lua/lua.go:170

		}
	}

	return index
}

func assign(field reflect.Value, val lua.LValue) error {
	switch field.Kind() {
	case reflect.String:
		s, ok := val.(lua.LString)
		if !ok {
			return fmt.Errorf("expected string, got %s", val.Type())
		}

		field.SetString(string(s))
	case reflect.Bool:
		b, ok := val.(lua.LBool)
		if !ok {
			return fmt.Errorf("expected boolean, got %s", val.Type())
		}

		field.SetBool(bool(b))
	case reflect.Int, reflect.Int64:
		n, ok := val.(lua.LNumber)
		if !ok {
			return fmt.Errorf("expected number, got %s", val.Type())
		}

		field.SetInt(int64(n))
	case reflect.Slice:
		return assignStructSlice(field, val)
	default:
		return fmt.Errorf("unsupported field kind %s", field.Kind())
	}

	return nil
}

View on GitHub (pinned to 328f4b4939)