Function narrowTypeByDiscriminant

test/fixtures/snapshot/typescript.js:70800–70816

(type, access, narrowType)

                return undefined;
            }
            function narrowTypeByDiscriminant(type, access, narrowType) {
                var propName = getAccessedPropertyName(access);
                if (propName === undefined) {
                    return type;
                }
                var removeNullable = strictNullChecks && ts.isOptionalChain(access) && maybeTypeOfKind(type, 98304 /* TypeFlags.Nullable */);
                var propType = getTypeOfPropertyOfType(removeNullable ? getTypeWithFacts(type, 2097152 /* TypeFacts.NEUndefinedOrNull */) : type, propName);
                if (!propType) {
                    return type;
                }
                propType = removeNullable ? getOptionalType(propType) : propType;
                var narrowedPropType = narrowType(propType);
                return filterType(type, function (t) {
                    var discriminantType = getTypeOfPropertyOrIndexSignature(t, propName);
                    return !(narrowedPropType.flags & 131072 /* TypeFlags.Never */) && isTypeComparableTo(narrowedPropType, discriminantType);
                });
            }
            function narrowTypeByDiscriminantProperty(type, access, operator, value, assumeTrue) {
                if ((operator === 36 /* SyntaxKind.EqualsEqualsEqualsToken */ || operator === 37 /* SyntaxKind.ExclamationEqualsEqualsToken */) && type.flags & 1048576 /* TypeFlags.Union */) {
                    var keyPropertyName = getKeyPropertyName(type);