Do not exit 1 if yarn already installed (#829)

I think it's bad idea to exit 1 in this case - because this script can't be used in pipeline or in ansible. Throwing exception breaks next movements. If Yarn already installed this script - it will warn and normally exited with exit code 0.
What do you think?

scripts/install-latest.sh

@@ -98,7 +98,7 @@ yarn_install() {
   if [ -d "$HOME/.yarn" ]; then
     printf "$red> ~/.yarn already exists, possibly from a past Yarn install.$reset\n"
     printf "$red> Remove it (rm -rf ~/.yarn) and run this script again.$reset\n"
-    exit 1
+    exit 0
   fi
 
   yarn_get_tarball