fix: allow empty V1 writes with non-nullable columns

rust/lance-file/src/versions/v1/writer/mod.rs

@@ -982,6 +982,37 @@ mod tests {
         assert_eq!(actual, batch);
     }
 
+    #[tokio::test]
+    async fn test_write_empty_non_nullable_string() {
+        let arrow_schema = Arc::new(ArrowSchema::new(vec![ArrowField::new(
+            "value",
+            DataType::Utf8,
+            false,
+        )]));
+        let schema = Schema::try_from(arrow_schema.as_ref()).unwrap();
+        let store = ObjectStore::memory();
+        let path = Path::from("/empty");
+        let mut file_writer = FileWriter::<NotSelfDescribing>::try_new(
+            &store,
+            &path,
+            schema.clone(),
+            &Default::default(),
+        )
+        .await
+        .unwrap();
+
+        file_writer
+            .write(&[RecordBatch::new_empty(arrow_schema)])
+            .await
+            .unwrap();
+        let summary = file_writer.finish().await.unwrap();
+        assert_eq!(summary.num_rows, 0);
+
+        let reader = FileReader::try_new(&store, &path, schema).await.unwrap();
+        let actual = reader.read_batch(0, .., reader.schema()).await.unwrap();
+        assert_eq!(actual.num_rows(), 0);
+    }
+
     #[tokio::test]
     async fn test_collect_stats() {
         // Validate:

rust/lance-file/src/versions/v1/writer/statistics.rs

@@ -642,8 +642,10 @@ impl StatisticsCollector {
             let max_value = Arc::new(builder.max_value.finish());
             let struct_fields = vec![
                 ArrowField::new("null_count", DataType::Int64, false),
-                ArrowField::new("min_value", field.data_type(), field.nullable),
-                ArrowField::new("max_value", field.data_type(), field.nullable),
+                // Bounds can be absent for empty pages regardless of the data field's
+                // nullability.
+                ArrowField::new("min_value", field.data_type(), true),
+                ArrowField::new("max_value", field.data_type(), true),
             ];
 
             let stats = StructArray::new(