Function checkDeleteExpressionMustBeOptional

test/fixtures/snapshot/typescript.js:78382–78389

(expr, symbol)

            return booleanType;
        }
        function checkDeleteExpressionMustBeOptional(expr, symbol) {
            var type = getTypeOfSymbol(symbol);
            if (strictNullChecks &&
                !(type.flags & (3 /* TypeFlags.AnyOrUnknown */ | 131072 /* TypeFlags.Never */)) &&
                !(exactOptionalPropertyTypes ? symbol.flags & 16777216 /* SymbolFlags.Optional */ : getFalsyFlags(type) & 32768 /* TypeFlags.Undefined */)) {
                error(expr, ts.Diagnostics.The_operand_of_a_delete_operator_must_be_optional);
            }
        }
        function checkTypeOfExpression(node) {
            checkExpression(node.expression);
            return typeofType;