Pull Request for Issue #25726 .

Summary of Changes

Checks that we're saving a plugin before continuing.

Testing Instructions

On a clean install try to install the "Testing Sample Data"

Expected result

Sample data completes all 8 steps successfully

Actual result

Sample data "hangs" after step 7 and console shows the following error

VM701:1 Uncaught SyntaxError: Unexpected token < in JSON at position 0
at JSON.parse ()
at onSuccess (sampledata-process.min.js?988a0f8a06606e444ef81cacee8fef3d:1)
at XMLHttpRequest.c.onreadystatechange (core.min.js?988a0f8a06606e444ef81cacee8fef3d:1)
onSuccess @ sampledata-process.min.js?988a0f8a06606e444ef81cacee8fef3d:1
c.onreadystatechange @ core.min.js?988a0f8a06606e444ef81cacee8fef3d:1
XMLHttpRequest.send (async)
a.request @ core.min.js?988a0f8a06606e444ef81cacee8fef3d:1
c.sampledataAjax @ sampledata-process.min.js?988a0f8a06606e444ef81cacee8fef3d:1
onSuccess @ sampledata-process.min.js?988a0f8a06606e444ef81cacee8fef3d:1
c.onreadystatechange @ core.min.js?988a0f8a06606e444ef81cacee8fef3d:1
XMLHttpRequest.send (async)
a.request @ core.min.js?988a0f8a06606e444ef81cacee8fef3d:1
c.sampledataAjax @ sampledata-process.min.js?988a0f8a06606e444ef81cacee8fef3d:1
onSuccess @ sampledata-process.min.js?988a0f8a06606e444ef81cacee8fef3d:1
c.onreadystatechange @ core.min.js?988a0f8a06606e444ef81cacee8fef3d:1
XMLHttpRequest.send (async)
a.request @ core.min.js?988a0f8a06606e444ef81cacee8fef3d:1
c.sampledataAjax @ sampledata-process.min.js?988a0f8a06606e444ef81cacee8fef3d:1
onSuccess @ sampledata-process.min.js?988a0f8a06606e444ef81cacee8fef3d:1
c.onreadystatechange @ core.min.js?988a0f8a06606e444ef81cacee8fef3d:1

Documentation Changes Required

No.