Why is the borrow checker essential for maintaining safety in Rust async code?

Example Concept: The borrow checker in Rust enforces rules that prevent data races by ensuring that only one mutable reference or multiple immutable references exist at any time. In async code, this is particularly important because tasks may yield control, allowing other tasks to run, which could lead to unsafe access patterns if not properly managed. The borrow checker guarantees that references remain valid and do not lead to undefined behavior, even when execution is paused and resumed.