fix: ensure worker reloads when importing node:* modules (#4962)

* fix: ensure worker reloads when importing `node:*` modules

* fix: ensure conflicting compatibility flags reported as user error

* fix: add type arguments to `seen` and `warnedPackaged`

.changeset/cuddly-apples-divide.md

@@ -0,0 +1,7 @@
+---
+"wrangler": patch
+---
+
+fix: ensure `wrangler dev` can reload without crashing when importing `node:*` modules
+
+The previous Wrangler release introduced a regression that caused reloads to fail when importing `node:*` modules. This change fixes that, and ensures these modules can always be resolved.

packages/wrangler/e2e/dev.test.ts

@@ -162,6 +162,7 @@ describe("basic dev tests", () => {
 					name = "${workerName}"
 					main = "src/index.ts"
 					compatibility_date = "2023-01-01"
+					compatibility_flags = ["nodejs_compat"]
 
 					[vars]
 					KEY = "value"
@@ -195,9 +196,12 @@ describe("basic dev tests", () => {
 
 			await worker.seed({
 				"src/index.ts": dedent`
+						import { Buffer } from "node:buffer";
 						export default {
 							fetch(request, env) {
-								return new Response("Updated Worker! " + env.KEY)
+								const base64Message = Buffer.from("Updated Worker!").toString("base64");
+								const message = Buffer.from(base64Message, "base64").toString();
+								return new Response(message + " " + env.KEY)
 							}
 						}`,
 			});
@@ -216,6 +220,7 @@ describe("basic dev tests", () => {
 						name = "${workerName}"
 						main = "src/index.ts"
 						compatibility_date = "2023-01-01"
+						compatibility_flags = ["nodejs_compat"]
 
 						[vars]
 						KEY = "updated"

packages/wrangler/src/__tests__/navigator-user-agent.test.ts

@@ -72,7 +72,7 @@ describe("isNavigatorDefined", () => {
 			assert(false, "Unreachable");
 		} catch (e) {
 			expect(e).toMatchInlineSnapshot(
-				`[AssertionError: Can't both enable and disable a flag]`
+				`[Error: Can't both enable and disable a flag]`
 			);
 		}
 	});

packages/wrangler/src/deployment-bundle/esbuild-plugins/nodejs-compat.ts

@@ -3,12 +3,6 @@ import chalk from "chalk";
 import { logger } from "../../logger";
 import type { Plugin } from "esbuild";
 
-// Infinite loop detection
-const seen = new Set();
-
-// Prevent multiple warnings per package
-const warnedPackaged = new Map();
-
 /**
  * An esbuild plugin that will mark any `node:...` imports as external.
  */
@@ -17,8 +11,16 @@ export const nodejsCompatPlugin: (silenceWarnings: boolean) => Plugin = (
 ) => ({
 	name: "nodejs_compat imports plugin",
 	setup(pluginBuild) {
-		seen.clear();
-		warnedPackaged.clear();
+		// Infinite loop detection
+		const seen = new Set<string>();
+
+		// Prevent multiple warnings per package
+		const warnedPackaged = new Map<string, string[]>();
+
+		pluginBuild.onStart(() => {
+			seen.clear();
+			warnedPackaged.clear();
+		});
 		pluginBuild.onResolve(
 			{ filter: /node:.*/ },
 			async ({ path, kind, resolveDir, ...opts }) => {
@@ -39,14 +41,12 @@ export const nodejsCompatPlugin: (silenceWarnings: boolean) => Plugin = (
 					// esbuild couldn't resolve the package
 					// We should warn the user, but not fail the build
 
-					if (!warnedPackaged.has(path)) {
-						warnedPackaged.set(path, [opts.importer]);
-					} else {
-						warnedPackaged.set(path, [
-							...warnedPackaged.get(path),
-							opts.importer,
-						]);
+					let pathWarnedPackaged = warnedPackaged.get(path);
+					if (pathWarnedPackaged === undefined) {
+						warnedPackaged.set(path, (pathWarnedPackaged = []));
 					}
+					pathWarnedPackaged.push(opts.importer);
+
 					return { external: true };
 				}
 				// This is a normal package—don't treat it specially

packages/wrangler/src/navigator-user-agent.ts

@@ -1,16 +1,16 @@
-import assert from "node:assert";
+import { UserError } from "./errors";
 
 export function isNavigatorDefined(
 	compatibility_date: string | undefined,
 	compatibility_flags: string[] = []
 ) {
-	assert(
-		!(
-			compatibility_flags.includes("global_navigator") &&
-			compatibility_flags.includes("no_global_navigator")
-		),
-		"Can't both enable and disable a flag"
-	);
+	if (
+		compatibility_flags.includes("global_navigator") &&
+		compatibility_flags.includes("no_global_navigator")
+	) {
+		throw new UserError("Can't both enable and disable a flag");
+	}
+
 	if (compatibility_flags.includes("global_navigator")) {
 		return true;
 	}