Statement is not valid inside a method/multiline lambda.
The code causing the problem looked this this:
Public Function GetSupplyList() As IEnumerable(Of SupplyItemDto) Implements IReadData.GetSupplyList
It took us a minute to realize that in Visual Basic.NET the Implements on a function has to be on the same line as the function. You can also use a line continuation character ("_") to fix the issue.
Of course, this is the exact opposite of Implements on a class where the Implements keyword has to be on the next line or you'll get "End of statement expected".