vcs: fixed test with null Context2D

Author: sehugg

.github/workflows/node.js.yml

@@ -17,9 +17,9 @@ jobs:
         node-version: [16.x]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v2
+      uses: actions/setup-node@v3
       with:
         node-version: ${{ matrix.node-version }}
         cache: 'npm'

src/common/baseplatform.ts

@@ -887,7 +887,7 @@ export abstract class BaseMachinePlatform<T extends Machine> extends BaseDebugPl
     if (!this.isRunning() && isRaster(this.machine) && this.machine.getRasterCanvasPosition) {
       const {x,y} = this.machine.getRasterCanvasPosition();
       if (x >= 0 || y >= 0) {
-        const ctx = this.video.getContext();
+        const ctx = this.video?.getContext();
         if (ctx) {
           drawCrosshair(ctx, x, y, 1);
         }

src/common/emu.ts

@@ -216,6 +216,7 @@ export class VectorVideo extends RasterVideo {
 }
 
 export function drawCrosshair(ctx:CanvasRenderingContext2D, x:number, y:number, width:number) {
+  if (!ctx?.setLineDash) return; // for unit testing
   ctx.fillStyle = 'rgba(0,0,0,0.25)';
   ctx.fillRect(x-2, 0, 5, 32767);
   ctx.fillRect(0, y-2, 32767, 5);

src/platform/vcs.ts

@@ -438,8 +438,10 @@ class VCSPlatform extends BasePlatform {
   updateVideoDebugger() {
     const {x,y} = this.getRasterCanvasPosition();
     if (x >= 0 || y >= 0) {
-      const ctx = this.canvas.getContext('2d');
-      drawCrosshair(ctx, x, y, 2);
+      const ctx = this.canvas?.getContext('2d');
+      if (ctx) {
+        drawCrosshair(ctx, x, y, 2);
+      }
     }
   }
 };