main:3295: attempt to index a nil value (field 'LUAROCKS_UNAME_S')

[trypsynth]

When attempting to run Luapak make on Windows, I get the following: main:3295: attempt to index a nil value (field 'LUAROCKS_UNAME_S')
stack traceback:
main:3295: in function main:3270
[C]: in function 'require'
main:8454: in function main:8453
[C]: in function 'require'
main:7468: in function main:7467
[C]: in function 'require'
main:624: in function main:623
[C]: in function 'require'
main:5310: in function main:5309
[C]: in function 'require'
main:10587: in main chunk