more fixes for flag set vs. array

src/lib/utils.js

@@ -156,7 +156,19 @@ exports.compilePositionLabel = (label, flags) => {
     return label
   }
   else {
-    const flags_set = new Set(flags.split(',').map(s=>s.trim()))
+    const flags_set = toFlagsSet(flags)
     return `${label} [${Array.from(flags_set).sort().join(',')}]`
   }
+}
+
+function toFlagsSet(flags) {
+  let flags_set
+    if (typeof(flags) == 'string'){
+      const flags_set = new Set(flags.split(',').map(s=>s.trim()))
+    } else if (flags.constructor === Array){
+      flags_set = new Set(flags)
+    } else if (flags.constructor === Set){
+      flags_set = flags
+    }
+  return flags_set
 }