* library version : 3.2.0 * Environment : Node **What did you expect to happen?** That it would print a normal assertion error **What actually happens** It fails with ``` TypeError: Cannot convert object to primitive value at String (<anonymous>) at /tmp/test1/node_modules/@sinonjs/referee/lib/interpolate-pos-arg.js:12:44 at Array.reduce (<anonymous>) at interpolatePosArg (/tmp/test1/node_modules/@sinonjs/referee/lib/interpolate-pos-arg.js:9:12) at Object.fail (/tmp/test1/node_modules/@sinonjs/referee/lib/define-assertion.js:30:27) at assertion (/tmp/test1/node_modules/@sinonjs/referee/lib/define-assertion.js:68:17) at Function.referee.<computed>.<computed> [as isUndefined] (/tmp/test1/node_modules/@sinonjs/referee/lib/define-assertion.js:93:26) at Object.<anonymous> (/tmp/test1/mytest.js:4:8) ``` **How to reproduce** ``` $ cat > mytest.js << EOF var referee = require("@sinonjs/referee"); var assert = referee.assert; assert.isUndefined(Object.create(null)); EOF node mytest.js ```