Enrich has no internal config, so we should not use it for parent sou…

…rce.

This should also cover the many places in test code we use null configurations.

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/io/stream/PlanStreamInput.java

@@ -29,6 +29,7 @@
 import org.elasticsearch.xpack.esql.Column;
 import org.elasticsearch.xpack.esql.core.expression.Attribute;
 import org.elasticsearch.xpack.esql.core.expression.NameId;
+import org.elasticsearch.xpack.esql.core.tree.Source;
 import org.elasticsearch.xpack.esql.core.type.EsField;
 import org.elasticsearch.xpack.esql.session.Configuration;
 
@@ -160,7 +161,7 @@ public Block[] readCachedBlockArray() throws IOException {
 
     @Override
     public String sourceText() {
-        return configuration.query();
+        return configuration == null ? Source.EMPTY.text() : configuration.query();
     }
 
     static void throwOnNullOptionalRead(Class<?> type) throws IOException {