What is more important: architecture or code?

The question itself is misleading. You need both.

Architecture defines the foundation of a solution. Code defines the details.
With a weak foundation, the house collapses. With bad windows and broken plumbing, the house survives, but living in it is painful.

Can mistakes be fixed?
Code-level mistakes are usually manageable. They can be fixed in place or rewritten.
Architectural mistakes are much harder. A poor choice of database or deployment model may take enormous effort to reverse months later.
By that time, teams often adapt to the mistake and it becomes a permanent characteristic of the system.

Why is that?
Architectural decisions are made for years, not quarters.
Some parts of a system do evolve frequently, and good architects account for this with evolutionary approaches.
Code, on the other hand, is highly dynamic.
Business demands change constantly, and the code reflects this every day.