CI is broken - change in latest Rust?

[jonathanpallant]

#983 did not pass CI but I think it should have done.

Error: failed to demangle defmt symbol {"package":"firmware","tag":"defmt_info","data":"extern "C" fn() -> i32: {}","disambiguator":"17031413998459764745","crate_name":"log"}: expected , or } at line 1 column 58

Nested " inside a JSON string, which is bad.

[Bluefinger]

I've been encountering this issue on a personal (private) project with compiling with nightly. Compiling with stable avoids this issue, but from what I could figure out, complex defmt formatting + many logging invocations caused the symbols to get broken in some way, and removing/changing how a logging call was made then caused the symbol breakage to change in non-obvious ways. I got my project to compile again and run by removing the logging calls that referenced more complex defmt formatting.

This has been occurring with latest nightly, so I suspect a regression there.