Fixed issue with dedicated channels strategy

The dedicated channels strategy would throw in `extractIdsFromSelector`
when the selector did not match certain criteria.
The code now checks these before selecting the strategy.

lib/processors/getStrategy.js

@@ -1,5 +1,21 @@
 import { Strategy } from '../constants';
 
+function canUseDedicatedChannels(selector) {
+    if (!selector || !selector._id) {
+        return false;
+    }
+
+    if (typeof selector._id === 'string') {
+        return true;
+    }
+
+    if (typeof selector._id === 'object' && '$in' in selector._id) {
+        return true;
+    }
+
+    return false;
+}
+
 /**
  * @param selector
  * @param options
@@ -15,7 +31,7 @@ export default function getStrategy(selector = {}, options = {}) {
         return Strategy.LIMIT_SORT;
     }
 
-    if (selector && selector._id) {
+    if (canUseDedicatedChannels(selector)) {
         return Strategy.DEDICATED_CHANNELS;
     }