Fix offscreencanvas undefined (#88)

* Suppress ReferenceError on some environments (i.e. older iOS)

* fix

* fix

* lint

---------

Co-authored-by: yuriha-chan <yuriha.tsuchiura@gmail.com>

packages/frontend/src/workers/test-webgl2.ts

@@ -1,3 +1,5 @@
+try {
+    // throw ReferenceError in Safari <= 16.3
     const canvas = new OffscreenCanvas(1, 1);
     const gl = canvas.getContext('webgl2');
     if (gl) {
@@ -5,3 +7,7 @@ if (gl) {
     } else {
         postMessage({ result: false });
     }
+} catch (err) {
+    // assert(e instanceof ReferenceError)
+    postMessage({ result: false });
+}