• "it works on my machine" is never a proper issue report.
• it seems like your code is incorrect when the universe dies out, i tried it with { 0, 1, 1 } and it reports the new dimensions as -4 x -6

I'm having an issue with this test "do_test(0, 3, 3, gen_0, 3, 3, gen_0);", I get "Test Crashed Caught unexpected signal: 6"
But when I run the function with the same arguments on my own I don't get any error.