SSA parser fails to parse allocations of `&mut function`

[TomAFrench]

I'm trying to create a testcase from the SSA output from a function in aztec-packages but I'm running into a parsing failure. A snippet of the failure is shown below.

 b0():
          call v64()
          v65 = allocate -> &mut u1
          store u1 0 at v65
          v67 = allocate -> &mut Field
          store Field 0 at v67

          v69 = allocate -> &mut function
                                 ^^^^^^^^
                                 Expected a type, found 'function'

          store Field 141 at v69
          v72 = make_array [Field 47] : [Field; 1]