From 60b094a9af087c48f7bfc5ff146f3bbfb29d4add Mon Sep 17 00:00:00 2001
From: Kurt Preston <github@kurtpreston.com>
Date: Mon, 4 Oct 2021 12:30:16 -0500
Subject: [PATCH] Fix chart crashing when max is defined but ticks are empty
 (#9641)

* Fix chart crashing when max is defined but ticks are empty

* Adding spec to reproduce scale bounds calculation error

Co-authored-by: Kurt Preston <kpreston@drw.com>
---
 src/scales/scale.linearbase.js   |  2 +-
 test/specs/scale.linear.tests.js | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/scales/scale.linearbase.js b/src/scales/scale.linearbase.js
index 0930d38f5..65631a618 100644
--- a/src/scales/scale.linearbase.js
+++ b/src/scales/scale.linearbase.js
@@ -128,7 +128,7 @@ function generateTicks(generationOptions, dataRange) {
 
   if (maxDefined && includeBounds && niceMax !== max) {
     // If the previous tick is too close to max, replace it with max, else add max
-    if (almostEquals(ticks[ticks.length - 1].value, max, relativeLabelSize(max, minSpacing, generationOptions))) {
+    if (ticks.length && almostEquals(ticks[ticks.length - 1].value, max, relativeLabelSize(max, minSpacing, generationOptions))) {
       ticks[ticks.length - 1].value = max;
     } else {
       ticks.push({value: max});
diff --git a/test/specs/scale.linear.tests.js b/test/specs/scale.linear.tests.js
index 3307c3962..9e8a61b6e 100644
--- a/test/specs/scale.linear.tests.js
+++ b/test/specs/scale.linear.tests.js
@@ -51,6 +51,29 @@ describe('Linear Scale', function() {
     expect(chart.scales.y.max).toBe(150);
   });
 
+  it('Should handle when only a max value is provided', () => {
+    var chart = window.acquireChart({
+      type: 'line',
+      data: {
+        datasets: [{
+          yAxisID: 'y',
+          data: [200]
+        }],
+      },
+      options: {
+        scales: {
+          y: {
+            type: 'linear',
+            max: 150
+          }
+        }
+      }
+    });
+
+    expect(chart.scales.y).not.toEqual(undefined); // must construct
+    expect(chart.scales.y.max).toBe(150);
+  });
+
   it('Should correctly determine the max & min of string data values', function() {
     var chart = window.acquireChart({
       type: 'bar',
-- 
2.47.2