Getfield with Measurements -> access to undefined reference

In this test model, an unexpected error is raised from getfield(…) when applied on an uninitialized struct on a field of type Measurements, and I do not find the reason:

module Test_getfield

using Measurements

mutable struct Values{StateType}
	function Values{StateType}(;L=1.0) where {StateType}
		obj = new()
		vfield = getfield(obj,:L)			
		setfield!(obj, :L, L)
		return obj

val1 = Values{Float64}()
@show val1

val2 = Values{Measurement{Float64}}(L=1.0±0.1)
@show val2

The constructor Values(…) first constructs an uninitialized instance via obj = new(). If getfield is called afterwards on a type such as Float64, everything is fine. If, however, the field is of type Measurements, then an error access to undefined reference is raised. Could someone give advice, how to fix this.

(Of course the code fragment above makes not much sense, because the call to getfield(…) has no effect; it is just used to demonstrate the issue).

Have found a solution: I need to inquire only the type of a field, and the call

vtype = fieldtype(typeof(obj), :L)

gives no error.