Fall back to default completion on other npm commands

npm-run-completion.zsh

@@ -12,6 +12,13 @@ _npm_run_completion() {
       local options=("${(@f)$(node -e "var pkg = require('$dir/$filename'); pkg.scripts && Object.keys(pkg.scripts).forEach(function(script) { console.log(script.replace(':', '\\\:')+':$ '+pkg.scripts[script]) })")}")
       _describe 'values' options
     fi
+  else
+    compadd -- $(COMP_CWORD=$((CURRENT-1)) \
+    COMP_LINE=$BUFFER \
+    COMP_POINT=0 \
+    npm completion -- "${words[@]}" \
+    2>/dev/null)
+    IFS=$si
   fi
 }