serializable structured errors

src/views/Unlock.svelte

@@ -1,13 +1,14 @@
 <script>
     import { invoke } from '@tauri-apps/api/tauri';
     import { createEventDispatcher } from 'svelte';
+    import { getRootCause } from '../lib/errors.js';
     import Button from '../ui/Button.svelte';
 
     export let appState;
 
     const dispatch = createEventDispatcher();
 
-    let error = null;
+    let errorMsg = null;
     let passphrase = '';
     async function unlock() {
         console.log('invoking unlock command.')
@@ -23,14 +24,20 @@
             }
         }
         catch (e) {
-            error = e;
             window.error = e;
+            if (e.code === 'GetSession') {
+                let root = getRootCause(e);
+                errorMsg = `Error response from AWS (${root.code}): ${root.msg}`;
+            }
+            else {
+                errorMsg = e.msg;
+            }
         }
     }
 </script>
 
-{#if error}
-    <div class="text-red-400">{error}</div>
+{#if errorMsg}
+    <div class="text-red-400">{errorMsg}</div>
 {/if}
 
 <form action="#" on:submit|preventDefault="{unlock}">