The binary and client.rb can both be run in plaintext mode (no arguments) and everything will work out fine. When both are run with the tls argument, the error can be reproduced, e.g ruby client.rb tls and ./target/debug/big-async-reader tls
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thread 'main' panicked at 'assertion failed: `(left == right)`
left: `32768`,
right: `0`', <::std::macros::panic macros>:5:6
stack backtrace: