[[null]] is a valid response (#13596)

* Repro for #13571: Display rows whose value is `null` (#13591) [ci skip]

* Reproduces #13571 

Co-authored-by: flamber <1447303+flamber@users.noreply.github.com>

* [[null]] is a valid response

Previously, this said that a result of `[[null]]` was an empty result
set, but in reality, it's a valid result set of a single column with a
null value.

Resolves #13571

Co-authored-by: Nemanja Glumac <31325167+nemanjaglumac@users.noreply.github.com>
Co-authored-by: flamber <1447303+flamber@users.noreply.github.com>

frontend/src/metabase/lib/dataset.js

@@ -20,9 +20,8 @@ type ColumnSetting = {
   enabled: boolean,
 };
 
-// Many aggregations result in [[null]] if there are no rows to aggregate after filters
 export const datasetContainsNoResults = (data: DatasetData): boolean =>
-  data.rows.length === 0 || _.isEqual(data.rows, [[null]]);
+  data.rows == null || data.rows.length === 0;
 
 /**
  * @returns min and max for a value in a column

frontend/test/metabase/scenarios/question/nulls.cy.spec.js

@@ -3,12 +3,39 @@ import {
   signInAsAdmin,
   openOrdersTable,
   popover,
+  withSampleDataset,
 } from "__support__/cypress";
 
 describe("scenarios > question > null", () => {
   before(restore);
   beforeEach(signInAsAdmin);
 
+  it("should display rows whose value is `null` (metabase#13571)", () => {
+    withSampleDataset(({ ORDERS }) => {
+      cy.request("POST", "/api/card", {
+        name: "13571",
+        dataset_query: {
+          database: 1,
+          query: {
+            "source-table": 2,
+            fields: [ORDERS.DISCOUNT],
+            filter: ["=", ORDERS.ID, 1],
+          },
+          type: "query",
+        },
+        display: "table",
+        visualization_settings: {},
+      });
+
+      // find and open previously created question
+      cy.visit("/collection/root");
+      cy.findByText("13571").click();
+
+      cy.log("**'No Results since at least v0.34.3**");
+      cy.findByText("No results!").should("not.exist");
+    });
+  });
+
   describe("aggregations with null values", () => {
     beforeEach(() => {
       cy.server();