#20376 Fixed issue with variables declarations and adjusted the notification message

Author: Serhiy Zhovnir

app/code/Magento/Ui/i18n/en_US.csv

@@ -190,4 +190,5 @@ CSV,CSV
 "Please enter at least {0} characters.","Please enter at least {0} characters."
 "Please enter a value between {0} and {1} characters long.","Please enter a value between {0} and {1} characters long."
 "Please enter a value between {0} and {1}.","Please enter a value between {0} and {1}."
-"was not uploaded","was not uploaded"
+"was not uploaded","was not uploaded"
+"The file upload field is disabled.","The file upload field is disabled."

app/code/Magento/Ui/view/base/web/js/form/element/file-uploader.js

@@ -344,16 +344,15 @@ define([
          * @param {Object} data - File data that will be uploaded.
          */
         onBeforeFileUpload: function (e, data) {
-            if (this.disabled()) {
-                this.notifyError($t('was not uploaded'));
-
-                return;
-            }
-
             var file     = data.files[0],
                 allowed  = this.isFileAllowed(file),
                 target   = $(e.target);
 
+            if (this.disabled()) {
+                this.notifyError($t('The file upload field is disabled.'));
+                return;
+            }
+
             if (allowed.passed) {
                 target.on('fileuploadsend', function (event, postData) {
                     postData.data.append('param_name', this.paramName);