In typescript-to-lua 1.37.1, transpiling a nested unary negation drops the parentheses and emits two consecutive - characters without a space (--), which Lua parses as a line comment.

let a = 5;
const b = -(-a);
console.log(b);

This compiles to:

a = 5
b = --a
print(b)

Because --a is treated as a comment to the end of the line, Lua executes b = print(b), printing nil instead of 5 (or failing with a syntax error when nothing follows on the next line).

printUnaryExpression only parenthesizes operands with strictly lower operator precedence, so nested unary minus operators are printed directly adjacent instead of -(-a) or - -a.

Credit: https://ucsbplse.github.io/