[20.09] fix undefined error in ui-file-source

[OlegZharkov]

What did you do?

added undefined check in ui-file-source.js

Why did you make this change?

(If fixing a bug, please add any relevant error or traceback)

TypeError: this._value is undefined
_getValue ui-file-source.js:82
value ui-file-source.js:71
e form-data.js:90
create form-data.js:109
render form-view.js:104
initialize form-view.js:25
initialize tool-form-base.js:25
View libs.chunk.js:1
r libs.chunk.js:1
r libs.chunk.js:1
t forms.js:46
N utilities.js:87
onActivate Index.vue:240
zt libs.chunk.js:7
n libs.chunk.js:7
zt libs.chunk.js:7
$emit libs.chunk.js:7
setNode Node.vue:292
te libs.chunk.js:7
Yt libs.chunk.js:7
promise callbackHt libs.chunk.js:7
te libs.chunk.js:7
update libs.chunk.js:7
update libs.chunk.js:7
notify libs.chunk.js:7
set libs.chunk.js:7
set libs.chunk.js:7
setData Node.vue:299
initData Node.vue:307
setNode Node.vue:289
onUpdate Index.vue:253
promise callbackonUpdate Index.vue:251
...

How to test the changes?

• Instructions for manual testing are as follows:
  1. Install this tool https://github.com/usegalaxy-eu/temporary-tools/tree/master/test/export
  2. try to add it in a workflow

For UI Components

• I've included a screenshot of the changes

[bgruening]

The packaging error looks scary but seems unrelated. Can we merge that @dannon?