@souenzzo Snippet above, thanks!

Added the exclusions as proposed by lein deps:

:dependencies [[org.clojure/clojure "1.9.0"]
                 [org.clojure/clojurescript "1.9.946"
                  :exclusions [[com.google.guava/guava]]]
[...]
  :profiles {:dev {:dependencies [[binaryage/devtools "0.9.9"]
                                  [figwheel-sidecar "0.5.15"
                                    :exclusions [[org.clojure/tools.nrepl]
                                                 [com.google.guava/guava]]]
[...]

Still blowing up:

$ rlwrap lein figwheel
Figwheel: Cleaning because dependencies changed
Figwheel: Cutting some fruit, just a sec ...
Exception in thread "main" java.lang.ExceptionInInitializerError
        at clojure.main.<clinit>(main.java:20)
Caused by: java.lang.NoSuchMethodError: com.google.common.base.Precondit
ions.checkState(ZLjava/lang/String;Ljava/lang/Object;)V, compiling:(clos
ure.clj:100:1)
        at clojure.lang.Compiler$DefExpr.eval(Compiler.java:470)
        at clojure.lang.Compiler.eval(Compiler.java:7067)
[...]

Any help on this?