fix(web-runtime): guard global error listeners for non-browser hosts

The module registered window error/unhandledrejection listeners at top
level, which threw under Node (the spec-api test runner) where
globalThis.addEventListener is absent. Register only when the API exists;
the real browser run is unaffected.

pkg/spec/src/web-runtime.ts

@@ -339,12 +339,14 @@ function recordException(error: unknown): void {
   });
 }
 
-globalThis.addEventListener("error", (event: ErrorEvent) => {
+if (typeof globalThis.addEventListener === "function") {
+  globalThis.addEventListener("error", (event: ErrorEvent) => {
     recordException(event.error ?? event.message);
-});
+  });
-globalThis.addEventListener("unhandledrejection", (event: PromiseRejectionEvent) => {
+  globalThis.addEventListener("unhandledrejection", (event: PromiseRejectionEvent) => {
     recordException(event.reason);
-});
+  });
+}
 
 function buildState(): unknown {
   return {