Fix bug where array element is undefined

Andy Hanson · Andy Hanson · commit 9b526a05b305 · 2018-08-13T17:21:20.000-07:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -3397,7 +3397,7 @@ namespace ts {
                             const arity = getTypeReferenceArity(type);
                             const tupleConstituentNodes = mapToTypeNodes(typeArguments.slice(0, arity), context);
                             const hasRestElement = (<TupleType>type.target).hasRestElement;
-                            if (tupleConstituentNodes && tupleConstituentNodes.length > 0) {
+                            if (tupleConstituentNodes && tupleConstituentNodes.length >= arity) {
                                 for (let i = (<TupleType>type.target).minLength; i < arity; i++) {
                                     tupleConstituentNodes[i] = hasRestElement && i === arity - 1 ?
                                         createRestTypeNode(createArrayTypeNode(tupleConstituentNodes[i])) :
