Preventing error when the branch isn't on upstream

themes/integral/fish_prompt.fish

@@ -6,6 +6,7 @@ end
 function _git_vs_upstream
   set count (command git rev-list --count --left-right "origin/$argv"...HEAD ^/dev/null)
 
+  if count
     switch $count
       case "" # no upstream
         echo ''
@@ -18,6 +19,7 @@ function _git_vs_upstream
       case '???'      # diverged from upstream
         echo 'u+'(echo $count | cut -f2)'-'(echo $count | cut -f1)
     end
+  end
 end
 
 function _is_git_dirty