There could be no lastEnabledChildRecord when there is no
firstEnabledChildRecord
- saves time by skipping findLastEnabledRecord() when the result is know
to be null,
- saves a test as isPresent(lastEnabledChildRecord) ==
isPresent(firstEnabledChildRecord)
This used to be valid code:
```
class Foo {
constructor() {
this.bar = ‘string’;
}
}
```
This will now fail since ‘bar’ is not explicitly
defined as a field. We now have to write:
```
class Foo {
bar:string; // << REQUIRED
constructor() {
this.bar = ‘string’;
}
}
```
