Address CR feedback

ahejlsberg · ahejlsberg · commit dd6365615dfe · 2018-10-11T08:45:47.000-07:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -9312,12 +9312,11 @@ namespace ts {
                         propType;
                 }
                 if (everyType(objectType, isTupleType) && isNumericLiteralName(propName) && +propName >= 0) {
-                    const restType = mapType(objectType, t => getRestTypeOfTupleType(<TupleTypeReference>t) || undefinedType);
-                    if (restType === undefinedType && accessNode) {
+                    if (accessNode && everyType(objectType, t => !(<TupleTypeReference>t).target.hasRestElement)) {
                         const indexNode = accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode.argumentExpression : accessNode.indexType;
                         error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType));
                     }
-                    return restType;
+                    return mapType(objectType, t => getRestTypeOfTupleType(<TupleTypeReference>t) || undefinedType);
                 }
             }
             if (!(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike)) {

Original file line number	Diff line number	Diff line change
`@@ -9312,12 +9312,11 @@ namespace ts {`
`9312`	`9312`	`propType;`
`9313`	`9313`	`}`
`9314`	`9314`	`if (everyType(objectType, isTupleType) && isNumericLiteralName(propName) && +propName >= 0) {`
`9315`		`- const restType = mapType(objectType, t => getRestTypeOfTupleType(<TupleTypeReference>t) \|\| undefinedType);`
`9316`		`- if (restType === undefinedType && accessNode) {`
	`9315`	`+ if (accessNode && everyType(objectType, t => !(<TupleTypeReference>t).target.hasRestElement)) {`
`9317`	`9316`	`const indexNode = accessNode.kind === SyntaxKind.ElementAccessExpression ? accessNode.argumentExpression : accessNode.indexType;`
`9318`	`9317`	`error(indexNode, Diagnostics.Property_0_does_not_exist_on_type_1, unescapeLeadingUnderscores(propName), typeToString(objectType));`
`9319`	`9318`	`}`
`9320`		`- return restType;`
	`9319`	`+ return mapType(objectType, t => getRestTypeOfTupleType(<TupleTypeReference>t) \|\| undefinedType);`
`9321`	`9320`	`}`
`9322`	`9321`	`}`
`9323`	`9322`	`if (!(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.StringLike \| TypeFlags.NumberLike \| TypeFlags.ESSymbolLike)) {`