Update canvas-renderer.ts (#2004)

* Update canvas-renderer.ts

Fixed an issue were a page wouldn't render.

Line 581 (now 582) threw exception: "Uncaught (in promise) DOMException: Failed to execute 'createPattern' on 'CanvasRenderingContext2D': The image argument is a canvas element with a width or height of 0."

* Update canvas-renderer.ts

src/render/canvas/canvas-renderer.ts

@@ -578,8 +578,10 @@ export class CanvasRenderer {
 
                 ctx.fillStyle = gradient;
                 ctx.fillRect(0, 0, width, height);
-                const pattern = this.ctx.createPattern(canvas, 'repeat') as CanvasPattern;
-                this.renderRepeat(path, pattern, x, y);
+                if ((width > 0) && (height > 0)) {
+					const pattern = this.ctx.createPattern(canvas, 'repeat') as CanvasPattern;
+					this.renderRepeat(path, pattern, x, y);
+				}
             } else if (isRadialGradient(backgroundImage)) {
                 const [path, left, top, width, height] = calculateBackgroundRendering(container, index, [
                     null,