Fix null pointer includes (#2657)

* Adds failing test for #2189

* Improves support for null values in includes

* nit

Author: flovilmart

spec/RestQuery.spec.js

@@ -235,4 +235,36 @@ describe('rest query', () => {
       done();
     });
   });
+
+  it('makes sure null pointers are handed correctly #2189', done => {
+    let object = new Parse.Object('AnObject');
+    let anotherObject = new Parse.Object('AnotherObject');
+    anotherObject.save().then(() => {
+      object.set('values', [null, null, anotherObject]);
+      return object.save();
+    }).then(() => {
+      let query = new Parse.Query('AnObject');
+      query.include('values');
+      return query.first();
+    }).then((result) => {
+      let values = result.get('values');
+      expect(values.length).toBe(3);
+      let anotherObjectFound = false;
+      let nullCounts = 0;
+      for(let value of values) {
+        if (value === null) {
+          nullCounts++;
+        } else if (value instanceof Parse.Object) {
+          anotherObjectFound = true;
+        }
+      }
+      expect(nullCounts).toBe(2);
+      expect(anotherObjectFound).toBeTruthy();
+      done();
+    }, (err) => {
+      console.error(err);
+      fail(err);
+      done();
+    });
+  });
 });

src/RestQuery.js

@@ -480,6 +480,9 @@ function includePath(config, auth, response, path) {
   let pointersHash = {};
   var objectIds = {};
   for (var pointer of pointers) {
+    if (!pointer) {
+      continue;
+    }
     let className = pointer.className;
     // only include the good pointers
     if (className) {
@@ -542,7 +545,7 @@ function findPointers(object, path) {
   }
 
   if (path.length == 0) {
-    if (object.__type == 'Pointer') {
+    if (object === null || object.__type == 'Pointer') {
       return [object];
     }
     return [];
@@ -564,15 +567,15 @@ function findPointers(object, path) {
 function replacePointers(object, path, replace) {
   if (object instanceof Array) {
     return object.map((obj) => replacePointers(obj, path, replace))
-              .filter((obj) => obj != null && obj != undefined);
+             .filter((obj) => typeof obj !== 'undefined');
   }
 
   if (typeof object !== 'object') {
     return object;
   }
 
   if (path.length === 0) {
-    if (object.__type === 'Pointer') {
+    if (object && object.__type === 'Pointer') {
       return replace[object.objectId];
     }
     return object;