creates top-level application error substate

wherehows-web/app/routes/datasets/dataset.js

@@ -500,14 +500,16 @@ export default Route.extend({
     const datasetUrl = `${datasetsUrlRoot}/${dataset_id}`;
 
     return Promise.resolve(getJSON(datasetUrl))
-      .then(({ status, dataset }) => {
-        return status === 'ok' && isPresent(dataset)
-          ? dataset
-          : Promise.reject(
-              new Error(`Request for ${datasetUrl} failed with: ${status}`)
-            );
-      })
-      .catch(() => ({}));
+      .then(({ status, dataset, message = '' }) => {
+        return status === 'ok' && isPresent(dataset) ?
+          dataset :
+          Promise.reject(
+            new Error(
+              `Request for ${datasetUrl} failed with status: ${status}.
+              ${message}`
+            )
+          );
+      });
   },
 
   actions: {

wherehows-web/app/templates/application-error.hbs

@@ -0,0 +1,9 @@
+<div class="wh-login-container">
+  <img src="/assets/assets/images/landing-logo.png"
+       alt="WhereHows Logo">
+  <p>Oops an error occurred!</p>
+
+  {{if model.message model.message ""}}
+
+  {{link-to "Back to safety" "application"}}
+</div>