refactor: collapse state diffs

package.json

@@ -37,6 +37,7 @@
     "@avocado/topdown": "^1.0.0",
     "glob": "^7.1.3",
     "immutablediff": "^0.4.4",
+    "is-plain-object": "2.0.4",
     "source-map-support": "^0.5.11"
   }
 }

traits/informed.js

@@ -1,4 +1,5 @@
 import * as I from 'immutable';
+import isPlainObject from 'is-plain-object';
 
 import {compose} from '@avocado/core';
 import {StateProperty, Trait} from '@avocado/entity';
@@ -30,6 +31,21 @@ class InformedBase extends Trait {
     }
   }
 
+  collapseStateDiff(diff) {
+    for (const index in diff) {
+      const value = diff[index];
+      if (isPlainObject(value)) {
+        if (!this.collapseStateDiff(value)) {
+          delete diff[index];
+        }
+      }
+    }
+    if (0 === Object.keys(diff).length) {
+      return null;
+    }
+    return diff;
+  }
+
   createIndexedReducer() {
     let previous = {};
     return (diff, indexed) => {
@@ -81,7 +97,7 @@ class InformedBase extends Trait {
         indexedEntities,
       );
     }
-    return diff;
+    return this.collapseStateDiff(diff);
   }
 
   get socket() {
@@ -100,6 +116,7 @@ class InformedBase extends Trait {
         // Take diff.
         let diff = stateSynchronizer.diff(this._informState);
         diff = this.reduceStateDiff(diff);
+        diff = diff ? diff : {};
         this._informState = stateSynchronizer.state;
         // Let the client know who they are.
         if (!this._sentSelf) {

yarn.lock

@@ -2609,7 +2609,7 @@ is-path-inside@^1.0.0:
   dependencies:
     path-is-inside "^1.0.1"
 
-is-plain-object@^2.0.1, is-plain-object@^2.0.3, is-plain-object@^2.0.4:
+is-plain-object@2.0.4, is-plain-object@^2.0.1, is-plain-object@^2.0.3, is-plain-object@^2.0.4:
   version "2.0.4"
   resolved "https://npm.i12e.cha0s.io/is-plain-object/-/is-plain-object-2.0.4.tgz#2c163b3fafb1b606d9d17928f05c2a1c38e07677"
   dependencies: