Legend does not work as expected

[ronsmits]

What version of OpenSCAD are you on?
version 2021.01

Describe the bug
adding two legends does not position correectly:

$outset_legends = true;
oem_row(3) legend("a",size=4,[0,-1]) legend("b",size=4,[0,1]) key();

The console shows:

[WARNING: undefined operation (-undefined) in file key.scad, line 180](https://github.com/rsheldiii/KeyV2/issues/180,/home/ron/src/ergodox/openSCAD-projects/key/src/key.scad) 
[WARNING: Unable to convert translate([0, 4.01429, undef]) parameter to a vec3 or vec2 of numbers in file key.scad, line 180](https://github.com/rsheldiii/KeyV2/issues/180,/home/ron/src/ergodox/openSCAD-projects/key/src/key.scad) 
[WARNING: undefined operation (-undefined) in file key.scad, line 180](https://github.com/rsheldiii/KeyV2/issues/180,/home/ron/src/ergodox/openSCAD-projects/key/src/key.scad) 
[WARNING: Unable to convert translate([0, -4.01429, undef]) parameter to a vec3 or vec2 of numbers in file key.scad, line 180](https://github.com/rsheldiii/KeyV2/issues/180,/home/ron/src/ergodox/openSCAD-projects/key/src/key.scad)

I am using the master branch, checked it out this morning

To Reproduce
see above
Additional context
Add any other context about the problem here.