EnumFieldSource throws AssertionError [LUCENE-9343]

When a doc id is smaller than a previsou one, I obtain an AssertionError. I check the Lucene code, and find that it is thrown from the following code of EnumFieldSource:

```java
public FunctionValues getValues(Map context, LeafReaderContext readerContext) throws IOException {
final NumericDocValues arr = DocValues.getNumeric(readerContext.reader(), field); return new IntDocValues(this) {
final MutableValueInt val = new MutableValueInt(); int lastDocID; private int getValueForDoc(int doc) throws IOException {
if (doc < lastDocID) {
throw new AssertionError("docs were sent out-of-order: lastDocID=" + lastDocID + " vs doc=" + doc);
}
lastDocID = doc;
int curDocID = arr.docID();
if (doc > curDocID) {
curDocID = arr.advance(doc);
}
if (doc == curDocID) {
return (int) arr.longValue();
} else {
return 0;
}
}
}
```

My code does not catch the exception. It catches IllegalArgumentException, because Lucene throws the exceptions for similar problems:

DocTermsIndexDocValues:

```java
protected int getOrdForDoc(int doc) throws IOException {
if (doc < lastDocID) {
throw new IllegalArgumentException("docs were sent out-of-order: lastDocID=" + lastDocID + " vs docID=" + doc);
}
lastDocID = doc;
int curDocID = termsIndex.docID();
if (doc > curDocID) {
curDocID = termsIndex.advance(doc);
}
if (doc == curDocID) {
return termsIndex.ordValue();
} else {
return -1;
}
}
```

BytesRefFieldSource:

```java
private BytesRef getValueForDoc(int doc) throws IOException {
if (doc < lastDocID) {
throw new IllegalArgumentException("docs were sent out-of-order: lastDocID=" + lastDocID + " vs docID=" + doc);
}
lastDocID = doc;
int curDocID = binaryValues.docID();
if (doc > curDocID) {
curDocID = binaryValues.advance(doc);
}
if (doc == curDocID) {
return binaryValues.binaryValue();
} else {
return null;
}
}
```

FloatFieldSource:

```java
private float getValueForDoc(int doc) throws IOException {
if (doc < lastDocID) {
throw new IllegalArgumentException("docs were sent out-of-order: lastDocID=" + lastDocID + " vs docID=" + doc);
}
lastDocID = doc;
int curDocID = arr.docID();
if (doc > curDocID) {
curDocID = arr.advance(doc);
}
if (doc == curDocID) {
return Float.intBitsToFloat((int)arr.longValue());
} else {
return 0f;
}
}
```

 EnumFieldSource throws a wrong exception. Can this problem be fixed?

---
Migrated from [LUCENE-9343](https://issues.apache.org/jira/browse/LUCENE-9343) by Ackel Filia

Locate EnumFieldSource.getValues and compare its out-of-order handling with DocTermsIndexDocValues, BytesRefFieldSource, and FloatFieldSource. Reproduce the decreasing-doc-ID case described in the issue and verify that the resulting exception matches the behavior of the surrounding field sources.

Written by the indexing model from the issue text.