tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(11,10): error TS2365: Operator '+' cannot be applied to types 'boolean' and 'boolean'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(12,10): error TS2365: Operator '+' cannot be applied to types 'Object' and 'Object'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(13,10): error TS2365: Operator '+' cannot be applied to types 'void' and 'void'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(14,10): error TS2365: Operator '+' cannot be applied to types 'boolean' and 'boolean'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(15,10): error TS2365: Operator '+' cannot be applied to types 'Object' and 'Object'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(16,10): error TS2365: Operator '+' cannot be applied to types 'void' and 'void'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(19,10): error TS2365: Operator '+' cannot be applied to types 'Number' and 'Number'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(20,10): error TS2365: Operator '+' cannot be applied to types 'boolean' and 'boolean'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(21,10): error TS2365: Operator '+' cannot be applied to types '{ a: string; }' and '{ a: string; }'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(22,11): error TS2365: Operator '+' cannot be applied to types 'void' and 'void'. tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts(23,11): error TS2365: Operator '+' cannot be applied to types '() => void' and '() => void'. ==== tests/cases/conformance/expressions/binaryOperators/additionOperator/additionOperatorWithNullValueAndInvalidOperator.ts (11 errors) ==== // If one operand is the null or undefined value, it is treated as having the type of the other operand. function foo(): void { return undefined } var a: boolean; var b: Object; var c: void; var d: Number; // null + boolean/Object var r1 = null + a; ~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'boolean' and 'boolean'. var r2 = null + b; ~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'Object' and 'Object'. var r3 = null + c; ~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'void' and 'void'. var r4 = a + null; ~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'boolean' and 'boolean'. var r5 = b + null; ~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'Object' and 'Object'. var r6 = null + c; ~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'void' and 'void'. // other cases var r7 = null + d; ~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'Number' and 'Number'. var r8 = null + true; ~~~~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'boolean' and 'boolean'. var r9 = null + { a: '' }; ~~~~~~~~~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types '{ a: string; }' and '{ a: string; }'. var r10 = null + foo(); ~~~~~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types 'void' and 'void'. var r11 = null + (() => { }); ~~~~~~~~~~~~~~~~~~ !!! error TS2365: Operator '+' cannot be applied to types '() => void' and '() => void'.