Properly fail when shims' counterparts are not present, fixes #6

Author: wfarr

libexec/nodenv-exec

@@ -25,6 +25,12 @@ if [ -z "$NODENV_VERSION" ]; then
   fi
 fi
 
+# if the specified NodeJS version lacks this bin, bail
+if [ ! -x "$NODENV_ROOT/versions/$NODENV_VERSION/bin/$1" ]; then
+  echo "nodenv: \`$1' does not exist for $NODENV_VERSION" >&2
+  exit 1
+fi
+
 export NODENV_VERSION
 
 # Put our bindir onto PATH