diff --git a/mod.ts b/mod.ts
index 846c64b..fad38c3 100644
--- a/mod.ts
+++ b/mod.ts
@@ -13,6 +13,14 @@ import { CPU, type CPUBackendLoader } from "./src/backends/cpu/mod.ts";
 import { WASM, type WASMBackendLoader } from "./src/backends/wasm/mod.ts";
 import type { BackendLoader } from "./src/core/engine.ts";
 
+onerror = () => {
+  if (typeof Deno == "undefined") {
+    throw new Error(
+      "Warning: Deno is not defined. Did you mean to import from ./web.ts instead of ./mod.ts?",
+    );
+  }
+};
+
 /**
  * The AUTO backend is chosen automatically based on the environment.
  */
diff --git a/src/core/engine.ts b/src/core/engine.ts
index 8fdc0a6..2d0ba5a 100644
--- a/src/core/engine.ts
+++ b/src/core/engine.ts
@@ -2,14 +2,6 @@ import { WASM } from "../backends/wasm/mod.ts";
 import type { Sequential } from "./mod.ts";
 import type { Backend, BackendType, NetworkConfig } from "./types.ts";
 
-onerror = () => {
-  if (typeof Deno == "undefined") {
-    throw new Error(
-      "Warning: Deno is not defined. Did you mean to import from ./web.ts instead of ./mod.ts?",
-    );
-  }
-};
-
 export interface BackendInstance {
   /**
    * Initialize the backend.