fix(search): Prevent duplicate results from search query

This is a temporary fix which adds defensive code to prevent duplicate results
from being returned from the thread search query which causes N1 to enter a loop
and freeze (#3001).

Duplicate results from the search query likely indicate that a thread
was indexed twice, which was not the case before. The cause for this is
still at large.

Author: jstejada

internal_packages/thread-search/lib/search-query-subscription.es6

@@ -48,14 +48,14 @@ class SearchQuerySubscription extends MutableQuerySubscription {
   }
 
   performLocalSearch() {
-    let dbQuery = DatabaseStore.findAll(Thread)
+    let dbQuery = DatabaseStore.findAll(Thread).distinct()
     if (this._accountIds.length === 1) {
       dbQuery = dbQuery.where({accountId: this._accountIds[0]})
     }
     dbQuery = dbQuery
     .search(this._searchQuery)
     .order(Thread.attributes.lastMessageReceivedTimestamp.descending())
-    .limit(30)
+    .limit(100)
 
     dbQuery.then((results) => {
       if (results.length > 0) {

internal_packages/thread-search/lib/search-store.es6

@@ -53,6 +53,10 @@ class SearchStore extends NylasStore {
 
   _onQueryChanged = (query) => {
     this._searchQuery = query;
+    if (this._searchQuery.length <= 1) {
+      this.trigger()
+      return
+    }
     this._compileResults();
     setTimeout(() => this._rebuildResults(), 0);
   }