Tryst::WrongThreadError

Raised by Interp#tcl_eval/#tcl_invoke - the two real chokepoints every higher-level Tcl call in this codebase funnels through, confirmed directly (only 6 LibTcl.eval*/do_one_event call sites exist in interp.cr; these two account for every one of them outside #initialize's own one-time setup and #mainloop's own event dispatch) - when called from a different OS thread than the one that created the interpreter. Not a TclError subclass: this is a Crystal/threading precondition violation caught before ever reaching Tcl, not something Tcl itself reported. See Interp#check_thread_affinity! for why this exists.