errorMessage leaked to global scope in non-strict mode, ReferenceError in strict mode

[ScottFreeCode]

If I run node --use_strict -e 'require("chai").expect("42").to.be.above(0)' I get:

ReferenceError: errorMessage is not defined

Instead of:

AssertionError: expected '42' to be a number or a date

If I run node -e 'try { require("chai").expect("42").to.be.above(0) } catch (ignore) { require("chai").expect(global.errorMessage).to.be.undefined }'

I get:

AssertionError: expected 'expected '42' to be a number or a date' to be undefined

---

There are probably other cases of variables being used without declaration; this just happens to be the one I ran into. Using --use_strict or --check-leaks in Mocha testing can help spot these, by the way!

[ScottFreeCode]

Thanks!