This article explains the new errors.AsType function in Go 1.26, which offers a type-safe way to check for specific error types. Unlike the older errors.As, it simplifies code by eliminating the need for intermediate variable declarations and reduces the risk of runtime panics. It's recommended for new code while errors.As remains available.

Designing custom error types in Go can lead to subtle bugs if best practices are not followed, particularly regarding the implementation of the Is method. A common pitfall arises when using the errors.Is function within an Is method, which can violate Go's error handling semantics and create misleading error equivalences. Developers should prioritize direct comparisons for error equality in custom Is methods to avoid such issues.