fish: don't source files if not interactive

dotfiles/fish/config.fish

@@ -7,6 +7,8 @@
 
 set -U fish_features stderr-nocaret qmark-noglob regex-easyesc
 
+if status is-interactive
+
     source {$__fish_config_dir}/env.fish
     source {$__fish_config_dir}/wm.fish
     source {$__fish_config_dir}/alias.fish
@@ -22,6 +24,7 @@ source {$__fish_config_dir}/colors.fish
         source {$__fish_config_dir}/prompt.fish
     {%@@ endif @@%}
 
+end
 
 function _fish_autoreload --on-signal SIGHUP
     source {$__fish_config_dir}/config.fish