fix: ignore undefined and null params on modifiers

lib/utils/getFields.js

@@ -1,3 +1,5 @@
+import isNil from "./isNil";
+
 /**
  * Taken from: https://github.com/Meteor-Community-Packages/meteor-collection-hooks/blob/master/collection-hooks.js#L194 and modified.
  * @param mutator
@@ -7,7 +9,7 @@ export default function getFields(mutator) {
     var fields = [];
     var topLevelFields = [];
 
-    Object.entries(mutator).forEach(function ([op, params]) {
+    Object.entries(mutator).filter(([_, params]) => !isNil(params)).forEach(function ([op, params]) {
         if (op[0] == '$') {
             Object.keys(params).forEach(function (field) {
                 // record the field we are trying to change

lib/utils/isNil.js

@@ -0,0 +1,3 @@
+export default function isNil(value) {
+    return value === null || value === undefined;
+}

lib/utils/testing/getFields.test.js

@@ -37,4 +37,24 @@ describe('Unit # getFields', function () {
     it('Should properly detected top level fields', function () {
         // TODO
     })
-});
+
+    it('Should ignore null or undefined params', function () {
+        let fields = run({
+            $set: {
+                a: {
+                    d: 1
+                },
+                'profile.test': 1
+            },
+            $inc: {
+                b: 1
+            },
+            $addToSet: undefined
+        }).fields;
+
+        assert.lengthOf(fields, 3);
+        assert.include(fields, 'a');
+        assert.include(fields, 'b');
+        assert.include(fields, 'profile.test');
+    })
+});

lib/utils/testing/index.js

@@ -1,2 +1,3 @@
 import './getFields.test';
-import './extractIdsFromSelector.test';
+import './extractIdsFromSelector.test';
+import './isNil.test';

lib/utils/testing/isNil.test.js

@@ -0,0 +1,13 @@
+import { assert } from 'chai';
+import run from '../isNil';
+
+describe('Unit # isNil', function () {
+    it('Should work', function () {
+        assert.isTrue(run(null));
+        assert.isTrue(run(undefined));
+        assert.isFalse(run(1));
+        assert.isFalse(run('1'));
+        assert.isFalse(run({}));
+        assert.isFalse(run([]));
+    });
+});