tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(2,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(3,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(4,10): error TS2365: Operator '+' cannot be applied to types 'null' and 'null'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts(5,10): error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'. ==== tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithOnlyNullValueOrUndefinedValue.ts (4 errors) ==== // bug 819721 var r1 = null + null; ~~~~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'. var r2 = null + undefined; ~~~~~~~~~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'. var r3 = undefined + null; ~~~~~~~~~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'null' and 'null'. var r4 = undefined + undefined; ~~~~~~~~~~~~~~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'undefined' and 'undefined'.