improve: show possible reasons when url fetch fails (#4295)

* improve: show possible reasons when url fetch fails
* Only check for fail reasons if no HTTP status code
* Check for mixed content errors first
* Harmonise error messages
* Set error source to 'fetch'
* improve: hide loading validator image (#4287)
* hide missing validator image
* Render nothing if validator badge has not loaded/received errors
* Revert style changes
* Allow images with data scheme (#4305)
* Add UnitTest for image
allows image elements with https scheme
* Test images with data scheme
* Add allowedSchemesByTag
* Fix error  Strings must use doublequote  quotes
* Add empty div (#4236)
if there are properties show an empty div
* v3.12.1 (#4311)
* v3.12.1
* Rebuild dist for v3.12.1
* Use window wrapper instead of direct reference
* Add trailing period to error messages
* improve readability

src/standalone/layout.jsx

@@ -21,6 +21,7 @@ export default class StandaloneLayout extends React.Component {
     let Container = getComponent("Container")
     let Row = getComponent("Row")
     let Col = getComponent("Col")
+    let Errors = getComponent("errors", true)
 
     const Topbar = getComponent("Topbar", true)
     const BaseLayout = getComponent("BaseLayout", true)
@@ -45,8 +46,8 @@ export default class StandaloneLayout extends React.Component {
           <div className="info">
             <div className="loading-container">
               <h4 className="title">Failed to load API definition.</h4>
-              <p>{lastErrMsg}</p>
-            </div>            
+              <Errors/>
+            </div>
           </div>
         }
         { loadingStatus === "failedConfig" &&