fix: crash when using colors per x

Author: farfromrefug

src/charting/data/BaseDataSet.ts

@@ -154,6 +154,10 @@ export abstract class BaseDataSet<T extends Entry> implements IDataSet<T> {
         return this.mColors;
     }
 
+    public getNbColors() {
+        return this.mColors.length;
+    }
+
     public getValueColors() {
         return this.mValueColors;
     }

src/charting/renderer/LineChartRenderer.ts

@@ -170,7 +170,9 @@ export class LineChartRenderer extends LineRadarRenderer {
         if (dataSet.getEntryCount() < 1) return false;
         this.mRenderPaint.setStrokeWidth(dataSet.getLineWidth());
         this.mRenderPaint.setPathEffect(dataSet.getDashPathEffect());
-        this.mRenderPaint.setColor(dataSet.getColor());
+        if (dataSet.getNbColors() === 1) {
+            this.mRenderPaint.setColor(dataSet.getColor());
+        }
         this.mRenderPaint.setStyle(Style.STROKE);
 
         const scaleX = this.mViewPortHandler.getScaleX();