Fix LineChart titles problem with single FlSpot, #1053

CHANGELOG.md

@@ -2,7 +2,8 @@
 * **BUGFIX** (by @imaNNeoFighT): Fix tooltip issue on negative bar charts, #978.
 * **IMPROVEMENT** (by @imaNNeoFighT): Use Container to draw axis-based charts border.
 * **FEATURE** (by @FlorianArnould) Add the ability to select the RadarChart shape (circle or polygon), #1047.
-
+* **BUGFIX** (by @imaNNeoFighT): Fix LineChart titles problem with single FlSpot, #1053.
+* 
 ## 0.51.0
 * **FEATURE** (by @imaNNeoFighT): Add `SideTitleWidget` to help you use it in [SideTitles.getTitlesWidget]. It's a wrapper around your widget. It keeps your provided `child` widget close to the chart. It has `angle` and `space` properties to handle margin and rotation. There is a `axisSide` property that you should fill, it has provided to you in the MetaData object. Check the below sample:
 ```dart

lib/src/chart/base/axis_chart/side_titles/side_titles_widget.dart

@@ -136,7 +136,11 @@ class SideTitlesWidget extends StatelessWidget {
         interval: interval,
       );
       axisPositions = axisValues.map((axisValue) {
-        var portion = (axisValue - axisMin) / (axisMax - axisMin);
+        final axisDiff = axisMax - axisMin;
+        var portion = 0.0;
+        if (axisDiff > 0) {
+          portion = (axisValue - axisMin) / axisDiff;
+        }
         if (isVertical) {
           portion = 1 - portion;
         }