Removing duplicated code

Author: navya9singh

src/compiler/checker.ts

@@ -15589,10 +15589,15 @@ m2: ${(this.mapper2 as unknown as DebugTypeMapper).__debugToString().split("\n")
                         return accessFlags & AccessFlags.IncludeUndefined ? getUnionType([indexInfo.type, undefinedType]) : indexInfo.type;
                     }
                     errorIfWritingToReadonlyIndex(indexInfo);
-                    if (accessFlags & AccessFlags.IncludeUndefined) {
-                        if (objectType.symbol && objectType.symbol.flags & (SymbolFlags.RegularEnum | SymbolFlags.ConstEnum) && (indexType.symbol && indexType.flags & TypeFlags.EnumLiteral && getParentOfSymbol(indexType.symbol) === objectType.symbol)) {
-                            return indexInfo.type;
-                        }
+                                        // When accessing an enum object with its own type,
+                    // e.g. E[E.A] for enum E { A }, undefined shouldn't
+                    // be included in the result type
+                    if ((accessFlags & AccessFlags.IncludeUndefined) &&
+                        !(objectType.symbol &&
+                            objectType.symbol.flags & (SymbolFlags.RegularEnum | SymbolFlags.ConstEnum) &&
+                            (indexType.symbol &&
+                            indexType.flags & TypeFlags.EnumLiteral &&
+                            getParentOfSymbol(indexType.symbol) === objectType.symbol))) {
                         return getUnionType([indexInfo.type, undefinedType]);
                     }
                     return indexInfo.type;