Solving the Unhandled Runtime Error TypeError: Cannot read properties of null in Next.js

Discover how to fix the `TypeError` in your Next.js application caused by null image properties and improve your code with practical solutions.
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This video is based on the question https://stackoverflow.com/q/78248451/ asked by the user 'Rashap Goyal' ( https://stackoverflow.com/u/23905041/ ) and on the answer https://stackoverflow.com/a/78249136/ provided by the user 'grekier' ( https://stackoverflow.com/u/1540177/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding and Fixing the Unhandled Runtime Error in Next.js

As a developer working with JavaScript frameworks, encountering runtime errors can be a common yet frustrating experience. One particular issue often faced when using Next.js is the Unhandled Runtime Error TypeError: Cannot read properties of null (reading 'default'). This error usually arises from trying to access properties of an object that doesn’t exist, resulting in an unexpected crash of your application.

In this guide, we'll explore why this issue occurs in a Next.js application and how to resolve it effectively using code modifications.

The Problem: What Causes the Error?

In the context of the code provided in the question, the error primarily arises from the use of an Image tag expecting a valid source (src) property. When this property is null, it leads to the type error since React cannot read the properties of null.

[[See Video to Reveal this Text or Code Snippet]]

If user?.picture is null, this line causes the described error when the component attempts to render the image.

The Symptoms:

The application throws an error when the Image component tries to access user?.picture.

Removing the Image component stops the error from occurring.

The Solution: Handling Null Values Gracefully

To tackle this problem, we can implement two strategies to ensure that our application functions smoothly while managing potential null values.

1. Conditional Rendering

One way to prevent the error is to conditionally render the Image component only if user?.picture is truthy (i.e., exists). This can be done as follows:

[[See Video to Reveal this Text or Code Snippet]]

2. Providing a Fallback Image

Another approach would be to display a default fallback image in case user?.picture is null. This way, you can always ensure that the component has a valid image source to render.

[[See Video to Reveal this Text or Code Snippet]]

Summary of Changes

Conditional Rendering: Only render the Image component if a valid src is available.

Fallback Image: Provide a default image path to ensure the Image component always has a valid source.

Conclusion

By implementing these strategies in your Next.js application, you can avoid the Unhandled Runtime Error TypeError: Cannot read properties of null. Not only does this enhance the stability of your application, but it also improves the overall user experience by ensuring that your application handles data gracefully.

If you encounter similar issues in the future, consider investigating the data being passed in your components and implementing effective checks to prevent such errors from occurring. Happy coding!

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