wasm_exec: Cross-port exit with code 1 change.

This cross-ports the following commit:
9eef964800

targets/wasm_exec.js

@@ -479,7 +479,7 @@
 		!global.process.versions.electron
 	) {
 		if (process.argv.length != 3) {
-			process.stderr.write("usage: go_js_wasm_exec [wasm binary] [arguments]\n");
+			console.error("usage: go_js_wasm_exec [wasm binary] [arguments]");
 			process.exit(1);
 		}
 
@@ -487,7 +487,8 @@
 		WebAssembly.instantiate(fs.readFileSync(process.argv[2]), go.importObject).then((result) => {
 			return go.run(result.instance);
 		}).catch((err) => {
-			throw err;
+			console.error(err);
+			process.exit(1);
 		});
 	}
 })();