Compiler errors and recursive nested functions

[Dylan Knutson]

Hello! I'm trying to make a deepMap function which operates on 
the deepest non-range element of an array. I think that this 
function should theoretically work, however there are some 
compiler errors that I can't quite understand.

Here's the code: http://dpaste.dzfl.pl/97918311
And the compiler error because DPaste's compiler service seems to 
be offline:

src\algorithm_util.d(26): Error: function 
algorithm_util.__unittestL34_5.deepMap!(__lambda4, int[]).deepMap 
is a nested function and cannot be accessed from 
algorithm_util.__unittestL34_5.deepMap!(__lambda4, 
int[][]).deepMap.__lambda2300!(int[]).__lambda2300DMD
v2.064 DEBUG

deepMap works just fine if I pass in an array that isn't nested, 
so this will work:

        auto a = [1, 2, 3];
        auto b = a.deepMap!(a => a + 1)();
        writeln(b);
        // "[2, 3, 4]"

Can someone explain what is going on?

Thank you,
Dylan Knutson