Update troubleshooting.md

doc/articles/troubleshooting.md

@@ -198,7 +198,7 @@ your setup. This also assumes that you have sudo privileges and the `php5enmod`
 commands available. It also assumes that you have `composer` in your path.
 
 ```sh
-echo 'function composer() { COMPOSER="$(which composer)" && sudo php5dismod -s cli xdebug ; $COMPOSER "$@" ; STATUS=$? ; sudo php5enmod -s cli xdebug ; return $STATUS ; }' >> ~/.bash_aliases
+echo 'function composer() { COMPOSER="$(which composer)" || { echo "Could not find composer in path" ; return 1 ; } && sudo php5dismod -s cli xdebug ; $COMPOSER "$@" ; STATUS=$? ; sudo php5enmod -s cli xdebug ; return $STATUS ; }' >> ~/.bash_aliases
 . ~/.bash_aliases
 ```