BorrowMutError in TlsfHeap when inserting into BTreeMap

[nathaniel-bennett]

I've run into an issue where my project returns the following error:

thread '<unnamed>' panicked at /root/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/embedded-alloc-0.6.0/src/tlsf.rs:62:58:
already borrowed: BorrowMutError
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Aborted

My Cargo.toml contains the following:

embedded-alloc = { version = "0.6.0", features = ["tlsf", "allocator_api"] }
critical-section = { version = "1.1", features = ["std"]}

...which should normally mean that std::sync::Mutex is used under the hood to deal with concurrent accesses. Since the TlsfHeap likewise uses this Mutex under the hood to control accesses into the RefCell, I have a feeling that this may be an error internal to the TlsfHeap implementation in some way.