Turbopack & Wagmi: Fixing Optional Peer Dependency Issues

Hey there, fellow web developers! If you're diving into the latest and greatest with Next.js 16, you've probably heard about Turbopack being the default. It's super speedy, and that's exciting! But sometimes, when you're working with libraries like wagmi, especially when you're dealing with optional peer dependencies, you might hit a snag. This article is all about a common issue that pops up with Turbopack and wagmi's optional connectors, and more importantly, how to fix it. We'll explore why it happens and the clever workarounds that can get your project building smoothly again.

The Challenge: Turbopack vs. Optional Dependencies in Wagmi

So, you've been following the recommendations, perhaps even closing previous issues like #4887, and embracing Turbopack as the go-to build tool for Next.js 16. That's a fantastic step towards optimizing your development experience. However, you might find yourself scratching your head when your project fails to build, specifically when @wagmi/connectors tries to dynamically import optional wallet SDKs that aren't actually installed in your project. This is a frustrating roadblock, especially when you're aiming for a lean and efficient build. The error message often looks something like this:

Module not found: Can't resolve '@coinbase/wallet-sdk'
  88 |
  89 |         async getProvider() {
> 90 |             const { createCoinbaseWalletSDK } = await import('@coinbase/wallet-sdk');

And it doesn't stop there; similar errors can pop up for other optional SDKs like @gemini-wallet/core or porto. This happens because, even though these are designed as optional peer dependencies and are imported dynamically (meaning they should only be loaded when needed), Turbopack, in its quest for build-time analysis, tries to resolve all import paths right from the get-go. If it encounters a path to a module that isn't present in your node_modules, it throws a fit and halts the build process. This behavior, while aiming for robustness, can be a bit of a curveball when dealing with flexible dependency management. The core of the problem lies in how the build tool interprets dynamic imports versus static analysis. In an ideal world, dynamic imports would be deferred until runtime, and Turbopack's analysis would be smart enough to understand that an optional dependency might not be there. But for now, we need a way to tell Turbopack, "Hey, it's okay if this isn't here right now."

We'll be looking at a specific scenario involving wagmi version 3.0.1, @wagmi/connectors version 7.0.2, next version 16.0.10, and a bun version 1.3.x. These versions and tools paint a clear picture of the environment where this issue is most likely to surface. The beauty of open-source development is that these challenges often lead to innovative solutions, and this particular hurdle is no exception. We're going to walk through the root cause of this build failure and then explore a practical workaround that will get your Next.js 16 project, powered by Turbopack and wagmi, back on track. It's all about understanding the tools and how they interact, and sometimes, a little configuration tweak is all it takes to bridge the gap between a cutting-edge build tool and a flexible library like wagmi.

Understanding the Root Cause: Static Analysis vs. Dynamic Imports

To truly appreciate the workaround, it's crucial to grasp why this problem occurs. Turbopack, being a next-generation build tool, is designed for blazing-fast builds through aggressive static analysis. This means it meticulously scans your codebase to understand dependencies, module graphs, and potential issues before your application even starts running. It's incredibly powerful for catching errors early and optimizing bundles. However, this very strength can become a challenge when dealing with patterns like optional peer dependencies and dynamic imports, which are common in libraries like wagmi to keep bundle sizes manageable.

When @wagmi/connectors tries to support a wide array of wallet SDKs, it can't realistically expect every user to install all of them. To solve this, it employs dynamic imports. For instance, when you want to use the Coinbase Wallet connector, the code might look something like this (simplified): import('@coinbase/wallet-sdk'). The import() function is a JavaScript feature that tells the environment to load a module only when that line of code is executed. This is brilliant for performance because if a user never uses the Coinbase Wallet, its SDK is never downloaded or processed by the bundler.

Here's where the conflict arises: Turbopack's static analysis engine, by default, doesn't necessarily defer the resolution of all dynamic import paths until runtime. Instead, it might parse these import() statements during the build phase and try to locate the specified modules immediately. If @coinbase/wallet-sdk (or any other optional SDK) isn't present in your node_modules directory—because you chose not to install it—Turbopack sees this as a missing dependency and fails the build. It's like a diligent librarian who insists on seeing every book on a shelf, even if you've told them you only need a specific one from a special collection that might be brought in later.

This behavior is not necessarily a bug in Turbopack or wagmi; rather, it's a nuance in how they interact. Turbopack is optimized for speed and certainty, while wagmi's use of optional dependencies is optimized for flexibility and reduced initial bundle size. The previous recommendation to switch to Turbopack, while sound for general performance, overlooked this specific interaction with optional peer dependencies. The issue isn't that the dependency can't be resolved, but that it's expected to be resolvable at build time even though it's designed to be optional and dynamically loaded. The solution, therefore, needs to address Turbopack's build-time analysis by providing it with a placeholder or a way to bypass the strict resolution requirement for these specific, optional modules.

The resolveAlias Workaround: A Practical Solution

Now that we understand the underlying issue, let's talk about the elegant solution: using Turbopack's resolveAlias configuration. This feature allows you to tell Turbopack to treat one module path as if it were another. In our case, we can use it to stub out the optional SDKs that Turbopack is complaining about. Instead of pointing to the actual (and potentially non-existent) SDK module, we'll redirect Turbopack to a simple, empty module file that we create.

Here’s how you implement this in your next.config.ts file:

// next.config.ts
import type { NextConfig } from 'next';

const nextConfig: NextConfig = {
  // ... other Next.js configurations
  turbopack: {
    resolveAlias: {
      "@coinbase/wallet-sdk": "./src/lib/wagmi/empty-module.js",
      "@gemini-wallet/core": "./src/lib/wagmi/empty-module.js",
      "porto": "./src/lib/wagmi/empty-module.js",
      // Add any other optional SDKs causing issues here
    },
  },
  // ...
};

export default nextConfig;

In this configuration, we're instructing Turbopack: "Whenever you encounter an import for @coinbase/wallet-sdk, @gemini-wallet/core, or porto, don't look for the actual package. Instead, resolve it as if it were ./src/lib/wagmi/empty-module.js."

Next, you need to create that empty-module.js file. Its job is incredibly simple: to provide a default export so that the import() statement doesn't fail, even though it's importing nothing useful. Create a file at the specified path (e.g., src/lib/wagmi/empty-module.js) with the following content:

// src/lib/wagmi/empty-module.js

// This module serves as a stub for optional dependencies that Turbopack might try to resolve at build time.
// It provides a default export to satisfy the import() statement without requiring the actual package.

export default {};

This empty-module.js file exports an empty object as its default. When Turbopack resolves the import to this file, the await import(...) statement will successfully complete, yielding an empty object. Since the code that uses these SDKs typically checks for the provider's existence or specific features after the import, this stubbed, empty object won't cause runtime errors. It effectively satisfies Turbopack's build-time requirements while maintaining the intended lazy-loading and optional nature of the original dependencies. This workaround is a testament to the flexibility of Turbopack's configuration options and a practical way to keep your development environment running smoothly.

Suggestions for a More Integrated Solution

While the resolveAlias workaround is highly effective for getting your project building with Turbopack and wagmi's optional dependencies, it does involve manual configuration. For a more seamless and maintainable experience, especially as the ecosystem evolves, it's worth considering some potential improvements that could be implemented within wagmi itself or its documentation. These suggestions aim to make the integration with modern build tools like Turbopack even smoother.

Firstly, tree-shaking unused connectors at the exports level could significantly reduce the build-time impact. If wagmi's public exports were structured in a way that only the explicitly imported connectors were considered for bundling, Turbopack might be less inclined to attempt resolving all potential optional dependencies. This would involve a more granular export strategy, where importing useConnect might not implicitly bring in the resolution logic for every single wallet connector unless that specific connector is also imported. Libraries are increasingly adopting this approach to optimize for tree-shaking, and it would be beneficial here.

Secondly, clearer documentation regarding the resolveAlias workaround specifically for Turbopack users would be incredibly valuable. While the workaround is effective, finding it might require digging through issues or community discussions. A dedicated section in the wagmi or @wagmi/connectors documentation explaining this Turbopack-specific behavior and providing the resolveAlias configuration snippet would empower developers immediately. This proactive documentation would save countless hours of debugging for those migrating to or using Next.js 16 with Turbopack.

Thirdly, exploring the possibility of separate entry points for each connector could offer another layer of control. If each connector had its own distinct entry point (e.g., wagmi/connectors/coinbase), developers could import only what they need. This makes it more explicit to bundlers which modules are required. While this might increase the number of package files, it could lead to more predictable behavior with static analysis tools like Turbopack, ensuring that only the explicitly imported connector's dependencies are considered for resolution.

These suggestions aren't about diminishing the value of the current workaround, which is a clever adaptation. Instead, they represent a forward-looking perspective on how libraries can better integrate with the evolving landscape of build tools, making the developer experience more robust and less prone to configuration-related friction. By considering these points, the wagmi ecosystem can continue to provide a top-tier developer experience, even as build tools and their capabilities advance.

Conclusion

Navigating the complexities of modern web development often involves a delicate balance between cutting-edge tools and established library patterns. The issue with Turbopack and wagmi's optional peer dependencies highlights this perfectly. While Turbopack's speed is a significant advantage for Next.js 16, its aggressive static analysis can clash with the dynamic import strategy used by libraries like wagmi to manage optional SDKs. The good news is that this challenge is surmountable.

The resolveAlias configuration in next.config.ts, coupled with a simple empty-module.js stub, provides a robust and immediate solution. By redirecting Turbopack's build-time resolution for these specific optional modules to a harmless placeholder, you can ensure your project builds successfully without compromising the intended flexibility of wagmi's connectors. This workaround is a practical example of how understanding your tools' configurations can empower you to overcome unexpected integration hurdles.

As the ecosystem matures, we might see even more integrated solutions, perhaps through improved tree-shaking or more explicit documentation. But for now, the resolveAlias method is your go-to technique for ensuring a smooth development experience with Turbopack and wagmi. Remember to keep your dependencies updated and stay engaged with the community – often, the solutions to these challenges are shared and refined collaboratively.

For further insights into Next.js and its build tools, a great resource is the official Next.js Documentation, which often contains detailed guides on configuration and best practices.