Tooltip fixes (getLabelAndValue on null controller, null getParsed)

src/plugins/plugin.tooltip.js

@@ -1182,7 +1182,11 @@ export class Tooltip extends Element {
 
     if (!inChartArea) {
       // Let user control the active elements outside chartArea. Eg. using Legend.
-      return lastActive;
+      // But make sure that active elements are still valid.
+      return lastActive.filter(i =>
+        this.chart.data.datasets[i.datasetIndex] &&
+        this.chart.getDatasetMeta(i.datasetIndex).controller.getParsed(i.index) !== undefined
+      );
     }
 
     // Find Active Elements for tooltips

test/specs/plugin.tooltip.tests.js

@@ -1667,6 +1667,91 @@ describe('Plugin.Tooltip', function() {
     });
   });
 
+  it('should tolerate datasets removed on events outside chartArea', async function() {
+    const dataset1 = {
+      label: 'Dataset 1',
+      data: [10, 20, 30],
+    };
+    const dataset2 = {
+      label: 'Dataset 2',
+      data: [10, 25, 35],
+    };
+    const chart = window.acquireChart({
+      type: 'line',
+      data: {
+        datasets: [dataset1, dataset2],
+        labels: ['Point 1', 'Point 2', 'Point 3']
+      },
+      options: {
+        plugins: {
+          tooltip: {
+            mode: 'index',
+            intersect: false
+          }
+        }
+      }
+    });
+
+    const meta = chart.getDatasetMeta(0);
+    const point = meta.data[1];
+    const expectedPoints = [jasmine.objectContaining({datasetIndex: 0, index: 1}), jasmine.objectContaining({datasetIndex: 1, index: 1})];
+
+    await jasmine.triggerMouseEvent(chart, 'mousemove', point);
+    await jasmine.triggerMouseEvent(chart, 'mousemove', {x: chart.chartArea.left - 5, y: point.y});
+
+    expect(chart.tooltip.getActiveElements()).toEqual(expectedPoints);
+
+    chart.data.datasets = [dataset1];
+    chart.update();
+
+    await jasmine.triggerMouseEvent(chart, 'mousemove', {x: 2, y: 1});
+
+    expect(chart.tooltip.getActiveElements()).toEqual([expectedPoints[0]]);
+  });
+
+  it('should tolerate elements removed on events outside chartArea', async function() {
+    const dataset1 = {
+      label: 'Dataset 1',
+      data: [10, 20, 30],
+    };
+    const dataset2 = {
+      label: 'Dataset 2',
+      data: [10, 25, 35],
+    };
+    const chart = window.acquireChart({
+      type: 'line',
+      data: {
+        datasets: [dataset1, dataset2],
+        labels: ['Point 1', 'Point 2', 'Point 3']
+      },
+      options: {
+        plugins: {
+          tooltip: {
+            mode: 'index',
+            intersect: false
+          }
+        }
+      }
+    });
+
+    const meta = chart.getDatasetMeta(0);
+    const point = meta.data[1];
+    const expectedPoints = [jasmine.objectContaining({datasetIndex: 0, index: 1}), jasmine.objectContaining({datasetIndex: 1, index: 1})];
+
+    await jasmine.triggerMouseEvent(chart, 'mousemove', point);
+    await jasmine.triggerMouseEvent(chart, 'mousemove', {x: chart.chartArea.left - 5, y: point.y});
+
+    expect(chart.tooltip.getActiveElements()).toEqual(expectedPoints);
+
+    dataset1.data = dataset1.data.slice(0, 1);
+    chart.data.datasets = [dataset1];
+    chart.update();
+
+    await jasmine.triggerMouseEvent(chart, 'mousemove', {x: 2, y: 1});
+
+    expect(chart.tooltip.getActiveElements()).toEqual([]);
+  });
+
   describe('events', function() {
     it('should not be called on events not in plugin events array', async function() {
       var chart = window.acquireChart({