fix(ios): guard source property and removed NSNull if it is nil

[vijaysingh-axway]

https://jira.appcelerator.org/browse/TIMOB-27354

[build]

	Messages
📖	💾 Here's the generated SDK zipfile.
📖	✅ All tests are passing Nice one! All 4336 tests are passing. (There are 471 tests skipped)
📖	✊ The commits in this PR match our conventions! Feel free to Rebase and Merge this PR when ready.

Generated by 🚫 dangerJS against 9a3b389

[sgtcoolguy]

LGTM

[Dankyi]

FR Failed - I had it run for the first time and it worked as it should but when I tried for a number of times after the first it failed for all the attempts. I followed the steps in the video from the attachment (https://jira.appcelerator.org/browse/TIMOB-27354)

Test Environment

Mac OS X 10.14.5
Node.js Version 10.16.3
Xcode 10.3 (build 10G8) - Xcode default
npm Version 6.9.0
Iphone 7 iOS Version 13.0

[lokeshchdhry]

FR Passed.

Studio Ver: 5.1.4.201909061933
SDK Ver: 8.2.1 local build
OS Ver: 10.14.5
Xcode Ver: Xcode 11.0
Appc NPM: 4.2.15
Appc CLI: 7.1.1
Daemon Ver: 1.1.3
Ti CLI Ver: 5.2.1
Alloy Ver: 1.14.1
Node Ver: 10.16.1
NPM Ver: 6.9.0
Java Ver: 10.0.2
IOS Simulator: Iphone XR IOS 13, Iphone XR IOS 12.2

[lokeshchdhry]

waiting to merge so that issue seen by @Dankyi can be verified.

[Dankyi]

FR Passed - "First/Second app on resume from url: undefined" prompt didn't showed up in all the tests I run.

Test Environment:

Mac OS X 10.14.5
Node.js Version 10.16.3
Xcode 10.3 (build 10G8) - Xcode default
npm Version 6.9.0
Iphone 7 iOS Version 13.0