fix(types): add optional additionalAngle parameter to RadialLinearScale.getPointPosition

[marina-semeia]

The getPointPosition method of RadialLinearScale accepts a third, optional additionalAngle parameter in its implementation (src/scales/scale.radialLinear.js):

getPointPosition(index, distanceFromCenter, additionalAngle = 0) {
  const angle = this.getIndexAngle(index) - HALF_PI + additionalAngle;
  // ...
}

It is already used internally (e.g. for pointLabels.centerPointLabels), but it is missing from the TypeScript definitions, so passing it from user code fails:

const scale = chart.scales.r as RadialLinearScale;
scale.getPointPosition(0, 100, Math.PI / 10);
// TS error: Expected 2 arguments, but got 3.

This is useful when extending RadarController to position points between grid lines instead of on them.

Changes

• Added the optional additionalAngle?: number parameter to RadialLinearScale.getPointPosition in src/types/index.d.ts.
• Added a type test in test/types/scales/radial_point_position.ts (fails with TS2554 without the fix, passes with it).

import { Chart, RadialLinearScale } from "chart.js";

const chart = new Chart(document.createElement("canvas"), {
  type: "radar",
  data: { labels: ["A", "B"], datasets: [{ data: [10, 20] }] }
});

const scale = chart.scales.r as RadialLinearScale;
const { x, y, angle } = scale.getPointPosition(0, 100, Math.PI / 2); // OK