Bug: S3 Image Upload breaks field if session expired.

[rnlambert7]

The Bug/Issue and replication: If your session has expired for whatever reason (time, timeout, server restart)(No indication your session was expired FYI) and you attempt to upload a new image it will fail (as it should) and then in the process change the value of the field from '' to {}. Upon signing in again, refreshing, etc, you cannot update the field and you will continue to receive angular errors. The only way to fix this is to go to the flat file db in /cms and reset the image filed back from {} to ''.

Here are the errors I received if it helps address this:
Upon trying to upload after session expired:

Possibly unhandled rejection: {"data":"Unauthorized","status":401,"config":{"method":"POST","transformRequest":[null],"transformResponse":[null],"jsonpCallbackParam":"callback","url":"/admin_api/img_upload","data":{"sid":"veHtI2A7QniHPA_ALFTwecp2VfRiGWHL","file":{"$ngfDataUrl":"data:image/png;base64,iVBORw.... continues on with base64 code of image..

Upon trying to upload while image field is {}:

angular.js:14642 Error: [$sce:itype] Attempted to trust a non-string value in a content requiring a string: Context: resourceUrl
http://errors.angularjs.org/1.6.5/$sce/itype?p0=resourceUrl
    at http://localhost:5000/admin/assets/vendor/angular/angular.js:116:12
    at trustAs (http://localhost:5000/admin/assets/vendor/angular/angular.js:19222:15)
    at Object.sce.(anonymous function) [as trustAsResourceUrl] (http://localhost:5000/admin/assets/vendor/angular/angular.js:20013:16)
    at Object.<anonymous> (http://localhost:5000/admin/assets/js/controllers/control_controllers/image_controller.js:36:29)
    at Object.invoke (http://localhost:5000/admin/assets/vendor/angular/angular.js:5040:19)
    at $controllerInit (http://localhost:5000/admin/assets/vendor/angular/angular.js:10960:34)
    at nodeLinkFn (http://localhost:5000/admin/assets/vendor/angular/angular.js:9840:35)
    at compositeLinkFn (http://localhost:5000/admin/assets/vendor/angular/angular.js:9149:13)
    at publicLinkFn (http://localhost:5000/admin/assets/vendor/angular/angular.js:9014:30)
    at Object.link (http://localhost:5000/admin/assets/vendor/angular/angular.js:28135:38) "<div ng-if="!globalizer &amp;&amp; terminated_context.type &amp;&amp; !terminated_context.control_path" ng-include="'/admin/controls/' + terminated_context.type + '_control/index.html'" class="ng-scope">"