better handle loading of flag details if getTarget returns null or undefined instead of {} for purged data

Not quite sure in what scenario it would be null or undefined...

src/controllers/mods.js

@@ -126,7 +126,7 @@ modsController.flags.detail = function (req, res, next) {
 			assignees: results.assignees,
 			type_bool: ['post', 'user', 'empty'].reduce(function (memo, cur) {
 				if (cur !== 'empty') {
-					memo[cur] = results.flagData.type === cur && !!Object.keys(results.flagData.target).length;
+					memo[cur] = results.flagData.type === cur && (!results.flagData.target || !!Object.keys(results.flagData.target).length);
 				} else {
 					memo[cur] = !Object.keys(results.flagData.target).length;
 				}