The "correct" way is highly context dependent with the added proviso that Zig assumes a low-level systems context.
In this context, adding data to an error may be expedient but 1) it has a non-trivial overhead on average and 2) may be inadvisable in some circumstances due to system state. I haven't written any systems in Zig yet but in low-level high-performance C++20 code bases we basically do the same thing when it comes to error handling. The conditional late binding of error context lets you choose when and where to do it when it makes sense and is likely to be safe.
A fundamental caveat of systems languages is that expediency takes a back seat to precision, performance, and determinism. That's the nature of the thing.
In this context, adding data to an error may be expedient but 1) it has a non-trivial overhead on average and 2) may be inadvisable in some circumstances due to system state. I haven't written any systems in Zig yet but in low-level high-performance C++20 code bases we basically do the same thing when it comes to error handling. The conditional late binding of error context lets you choose when and where to do it when it makes sense and is likely to be safe.
A fundamental caveat of systems languages is that expediency takes a back seat to precision, performance, and determinism. That's the nature of the thing.