It sounds like you're referring to a recent change in TypeScript 5.6.

In the past, if you imported a module that didn't exist, TypeScript wouldn't warn or error about it. However, with the introduction of `noUncheckedSideEffectImports` in TypeScript 5.6, this behavior has changed.

Now, when you try to import a non-existent file, TypeScript will throw an error, indicating that the import is causing side effects and therefore needs to be checked.

This change aims to help developers catch potential issues earlier by making imports more explicit and safer. However, it might require some adjustments in existing codebases where this behavior was previously tolerated.

Are you experiencing any issues with this new behavior, or do you think this change will improve the overall quality of your TypeScript projects?