Merge pull request #1259 from FlowFuse/1255-multi-line-chart-does-not…

…-draw-line-for-first-point-on-additional-topics

Fixed: multi line chart does not draw line for first point on additional topics

ui/src/widgets/ui-chart/UIChart.vue

@@ -361,9 +361,12 @@ export default {
                 const radius = this.props.pointRadius ? this.props.pointRadius : 4
 
                 // ensure we have a datapoint for the relevant series
-                const data = Array(sLabels.length + 1).fill({})
+                const data = Array(sLabels.length).fill({})
                 if (xIndex === -1) {
-                    data[xLabels.length] = datapoint
+                    // Add the new x-value to xLabels
+                    xLabels.push(datapoint.x)
+                    // Assign the datapoint to the new index (last position)
+                    data[xLabels.length - 1] = datapoint
                 } else {
                     data[xIndex] = datapoint
                 }