**TypeScript Version:** master **Code** ``` ts (''.match(/ /) || []).map(s => s.toLowerCase()); ``` **Expected behavior:** ``` $ node built/local/tsc.js --lib es6 --strictNullChecks index.ts ``` **Actual behavior:** ``` $ node built/local/tsc.js --lib es6 --strictNullChecks index.ts index.ts(1,1): error TS2349: Cannot invoke an expression whose type lacks a call signature. ```