A stale mount point can cause issues

[mfikes]

I had a stale mount from an older copy of Ambly (because I had Ctrl-C'd out of the REPL). Stale mounts appear to cause problems like this:

java.io.FileNotFoundException: /Volumes/Ambly-10.0.1.13/cljs/core.cljs (Input/output error)
    at java.io.FileOutputStream.open(Native Method)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
    at clojure.java.io$fn__8704.invoke(io.clj:230)
    at clojure.java.io$fn__8641$G__8604__8648.invoke(io.clj:69)
    at clojure.java.io$fn__8678.invoke(io.clj:166)
    at clojure.java.io$fn__8654$G__8608__8661.invoke(io.clj:69)
    at clojure.java.io$writer.doInvoke(io.clj:119)
    at clojure.lang.RestFn.invoke(RestFn.java:410)
    at clojure.lang.AFn.applyToHelper(AFn.java:154)
    at clojure.lang.RestFn.applyTo(RestFn.java:132)
    at clojure.core$apply.invoke(core.clj:626)
    at clojure.core$spit.doInvoke(core.clj:6403)
    at clojure.lang.RestFn.invoke(RestFn.java:425)
    at cljs.closure$jar_file_to_disk.invoke(closure.clj:372)
    at cljs.closure$compile_from_jar.invoke(closure.clj:389)
    at cljs.closure$eval3125$fn__3126.invoke(closure.clj:404)
    at cljs.closure$eval3066$fn__3067$G__3057__3074.invoke(closure.clj:305)
    at cljs.closure$compile.invoke(closure.clj:336)
    at ambly.repl.jsc$setup.invoke(jsc.clj:220)
    at ambly.repl.jsc.JscEnv._setup(jsc.clj:281)
    at cljs.repl$repl_STAR_$fn__3796.invoke(repl.clj:629)
    at cljs.repl$repl_STAR_.invoke(repl.clj:628)