'already mutably borrowed: BorrowError': src/plugin/host.rs:359

[SamWindell]

I'm sporadically getting some panics firing. I'm seeing this on any OS.

Error: 1 [ERROR] thread 'main' panicked at 'already mutably borrowed: BorrowError': src/plugin/host.rs:359
Error: 1 [ERROR] thread 'main' panicked at 'already borrowed: BorrowMutError': src/plugin/host.rs:309
Error: 1 [ERROR] thread 'main' panicked at 'panic in a destructor during cleanup': core/src/panicking.rs:229

Looking at the first error message, it's related to code for checking if there were main thread callbacks requested:

clap-validator/src/plugin/host.rs

Line 359 in 2f71690

let instances = self.instances.borrow();

A recent change in my plugin is more frequent use of request_callback().