Vary code style to new homologated manner.

src/canvas.js

@@ -17,7 +17,7 @@ const lineFn = line()
 const pathGroupElems = new Map()
 
 let stroke_colour = "blue"
-export var stroke_radius = 1
+export let stroke_radius = 1
 export const MIN_STROKE_RADIUS = 0.1
 export const MAX_STROKE_RADIUS = 3.9
 
@@ -92,7 +92,7 @@ const createPathElem = (d, width) => {
 export const renderPath = (id, points) => {
   points = points.filter(([x]) => x != null)
   let colour = ""
-  var radius = 0
+  let radius = 0
 
   // Split up points into completely non-erased segments.
   let segments = [[]]