On the latest Rooibos release `5.12.0`, stepping into the `m.stubCall` method: ``` function stubCall(invocation as dynamic, stubOrReturnValue = invalid as dynamic, functionName = "" as string) as object ``` The `stubOrReturnValue` param throws an error if it's not defined as a function: `.endsWith("Function")`. Based on the way this param is named, it appears to be a regression?