test initializing optimizely core with bad datafile returns nil optimizely object. test breaks right now since error handler in project config is nil

Author: wangjoshuah

OptimizelySDKCore/OptimizelySDKCoreTests/OPTLYBuilderTest.m

@@ -129,4 +129,11 @@ - (void)testInitializationWithoutBuilder {
     XCTAssertNil(optimizely);
 }
 
+- (void)testBuilderReturnsNilWithBadDatafile {
+    Optimizely *optimizely = [Optimizely initWithBuilderBlock:^(OPTLYBuilder * _Nullable builder) {
+        builder.datafile = [[NSData alloc] init];
+    }];
+    XCTAssertNil(optimizely);
+}
+
 @end