#2081 #2117 fix prop type in react-native

[danielduan]

Issue:

#2081 #2117
There is an optional prop was listed as required

What I did

Changed it to optional and added a defaultProp

How to test

Is this testable with jest or storyshots?
yes, passes the test with no changes
Does this need a new example in the kitchen sink apps?
no
Does this need an update to the documentation?
no
If your answer is yes to any of these, please make sure to include it in your PR.

[codecov]

Codecov Report

Merging #2185 into master will decrease coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #2185      +/-   ##
==========================================
- Coverage   21.43%   21.42%   -0.01%     
==========================================
  Files         263      263              
  Lines        5803     5805       +2     
  Branches      693      699       +6     
==========================================
  Hits         1244     1244              
+ Misses       4028     4026       -2     
- Partials      531      535       +4

Impacted Files	Coverage Δ
...t-native/src/preview/components/StoryView/index.js	0% <0%> (ø)	⬆️
...-native/src/preview/components/OnDeviceUI/index.js	0% <0%> (ø)	⬆️
app/react/src/server/utils.js	0% <0%> (-53.58%)	⬇️
lib/ui/src/modules/ui/routes.js	0% <0%> (ø)	⬆️
.../src/manager/containers/CommentsPanel/dataStore.js	34.97% <0%> (ø)	⬆️
addons/knobs/src/components/types/Color.js	8.1% <0%> (ø)	⬆️
lib/ui/src/modules/shortcuts/actions/shortcuts.js	6.25% <0%> (ø)	⬆️
lib/ui/src/modules/ui/components/menu_item.js	19.14% <0%> (ø)	⬆️
addons/info/src/components/markdown/htags.js	30% <0%> (ø)	⬆️
addons/knobs/src/components/PropField.js	10.63% <0%> (ø)	⬆️
... and 18 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update aebe01f...f11e285. Read the comment docs.