Fix elemMatch null object array handling

packages/node_modules/pouchdb-selector-core/src/in-memory-filter.js

@@ -219,9 +219,15 @@ var matchers = {
       return false;
     }
 
-    if (typeof docFieldValue[0] === 'object' &&  docFieldValue[0] !== null) {
+    var userValueKeys = Object.keys(userValue);
+    var userValueHasNonOperator = userValueKeys.some(function (key) {
+      return key.indexOf('$') !== 0;
+    });
+
+    if (userValueHasNonOperator) {
       return docFieldValue.some(function (val) {
-        return rowFilter(val, userValue, Object.keys(userValue));
+        return typeof val === 'object' && val !== null &&
+          rowFilter(val, userValue, userValueKeys);
       });
     }
 

tests/find/test-suite-1/test.elem-match.js

@@ -80,6 +80,26 @@ describe('test.elem-match.js', () => {
     }).should.deep.equal(['2', '3']);
   });
 
+  it('with null element in object array', async () => {
+    const db = context.db;
+    const docs = [
+      {_id: 'null-after-object', test: [{foo: 'blub'}, null]},
+      {_id: 'only-null', test: [null]},
+      {_id: 'no-match', test: [{foo: 'nope'}, null]}
+    ];
+
+    await db.bulkDocs(docs);
+    const resp = await db.find({
+      selector: {
+        test: {$elemMatch: {foo: 'blub'}},
+      },
+      fields: ['_id']
+    });
+    resp.docs.map((doc) => {
+      return doc._id;
+    }).should.deep.equal(['null-after-object']);
+  });
+
   it('should error for non-object query value', async () => {
     const db = context.db;
     try {