Avoid releasing retainables if there are pending writes (#1589)

Summary:
Pull Request resolved: #1589

Avoid releasing retainables at the end of the batch if there were writes while processing them.  This could happen, for example, if there are effects which monitor changes and then also write state.

This error is currently superfulous for the open source release where garbage collection is enabled but not used.

Addresses #1582

Reviewed By: davidmccabe

Differential Revision: D33965759

fbshipit-source-id: 904f6e1778f7ba864cea54f0e3f2641e995834c1

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## UPCOMING
 
+- Avoid spurious console errors from effects when calling `setSelf()` from `onSet()` handlers. (#1589)
+
 **_Add new changes here as they land_**
 
 - `shouldNotBeFrozen` now works in JS environment without `Window` interface. (#1571)

packages/recoil/core/Recoil_RecoilRoot.js

@@ -209,7 +209,7 @@ function endBatch(store: Store) {
 
     // Ignore commits that are not because of Recoil transactions -- namely,
     // because something above RecoilRoot re-rendered:
-    if (nextTree === null) {
+    if (nextTree == null) {
       return;
     }
 
@@ -232,7 +232,11 @@ function endBatch(store: Store) {
     storeState.previousTree = null;
 
     if (gkx('recoil_memory_managament_2020')) {
-      releaseScheduledRetainablesNow(store);
+      // Only release retainables if there were no writes during the end of the
+      // batch.  This avoids releasing something we might be about to use.
+      if (nextTree == null) {
+        releaseScheduledRetainablesNow(store);
+      }
     }
   } finally {
     storeState.commitDepth--;