Conflict with WYSIWYG widget plugins

With either of the following plugins installed and activated:

* Black Studio TinyMCE Widget v2.3.2
* WP Editor Widget v0.5.5

Going to the Appearance > Widgets page in WordPress Admin throws the following console error in Chrome (and subsequently causes plugins to fail and be unusable)

Uncaught ReferenceError: formstack_tinymce is not defined
    at new <anonymous> (https://seattleafwa.org/wp/wp-content/plugins/formstack/tinymce/plugin.js?wp-mce-4506-20170408:4:13)
    at Array.e (https://seattleafwa.org/wp/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4506-20170408:12:26858)
    at n (https://seattleafwa.org/wp/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4506-20170408:4:1533)
    at L.init (https://seattleafwa.org/wp/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4506-20170408:12:27411)
    at L.<anonymous> (https://seattleafwa.org/wp/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4506-20170408:12:25336)
    at Array.<anonymous> (https://seattleafwa.org/wp/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4506-20170408:5:11775)
    at n (https://seattleafwa.org/wp/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4506-20170408:4:1533)
    at v (https://seattleafwa.org/wp/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4506-20170408:5:11722)
    at c.(anonymous function).c.(anonymous function).c.(anonymous function).c.(anonymous function) (https://seattleafwa.org/wp/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4506-20170408:5:11656)
    at HTMLScriptElement.o (https://seattleafwa.org/wp/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4506-20170408:5:10514)

The file:line referenced in the error is:

plugin.js?wp-mce-4506-20170408:4
———————————————–

(function () {
	tinymce.PluginManager.add('formstack', function (ed, url) {
		ed.addButton('formstack', {
			title  : formstack_tinymce.button,

Interestingly with both of those plugins active, but formstack plugin deactivated, they don’t cause a conflict with eachother — merely, they both cause conflict and throw errors when the formstack plugin is enabled.

Best guess this is some kind of scope error? Recently introduced?