Clojurians Log v2

I'm struggling to get vim-fireplace (through cider-nrepl) working on a boot project, but I'm finding conflicting examples for how to configure it, and get errors both ways.

following this https://github.com/clojure-emacs/cider-nrepl#via-boot I get

java.lang.Thread.run              Thread.java:  834
java.util.concurrent.ThreadPoolExecutor$Worker.run  ThreadPoolExecutor.java:  628
 java.util.concurrent.ThreadPoolExecutor.runWorker  ThreadPoolExecutor.java: 1128
               java.util.concurrent.FutureTask.run          FutureTask.java:  264
                                               ...
               clojure.core/binding-conveyor-fn/fn                 core.clj: 2030
                                 boot.core/boot/fn                 core.clj: 1031
                               boot.core/run-tasks                 core.clj: 1022
              boot.task.built-in/eval2512/fn/fn/fn             built_in.clj:  492
                                clojure.core/deref                 core.clj: 2320
                                               ...
                 boot.task.built-in/eval2512/fn/fn             built_in.clj:  489
                                clojure.core/apply                 core.clj:  665
                                               ...
                            boot.core/launch-nrepl                 core.clj: 1300
                            boot.core/launch-nrepl                 core.clj: 1313
                            boot.repl/launch-nrepl                 repl.clj:   60
                     boot.repl-server/start-server          repl_server.clj:   72
                                clojure.core/apply                 core.clj:  665
                                               ...
                      nrepl.server/default-handler               server.clj:   80
                      nrepl.server/default-handler               server.clj:   90
                              clojure.core/comp/fn                 core.clj: 2569 (repeats 8 times)
java.lang.NullPointerException:
    clojure.lang.ExceptionInfo:
    line: 41

following the first example here https://github.com/boot-clj/boot/wiki/Cider-REPL I get https://pastebin.com/ihGsU0ki when I try to evaluate something.

that latter error looks like things are connecting, but fireplace and nrepl are speaking different dialects?

if I drop the *default-middleware* call from that latter guide, I get

{'status': ['eval-error', 'done'], 'id': 'fireplace-archlinux-1562898025-39', 'out': '             ^[[1;31mjava.lang.RuntimeException^[[m: ^[[3mUnable to resolve symbol: let
in this context^[[m^@^[[1;31mclojure.lang.Compiler$CompilerException^[[m: ^[[3mSyntax error compiling at (1:2).^[[m^@', 'root-ex': 'class clojure.lang.Compiler$CompilerException', 'ex': 'class clojure.lang.Compiler$CompilerException', 'session': ['7c44ecf6-5b1a
-4e42-9323-51e2fa447073']}

discovered a workaround: use Clojure 1.9.0, not 1.10.1. not satisfying, but it'll do for now.