From e0799181d93d9548c4b42193fdaba78adc45d23c Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Wed, 22 Apr 2020 20:53:18 +0200
Subject: [PATCH] show error when mount() fails in SwitchView

---
 src/ui/web/general/SwitchView.js |  9 ++++++++-
 src/ui/web/general/error.js      | 12 ++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 src/ui/web/general/error.js

diff --git a/src/ui/web/general/SwitchView.js b/src/ui/web/general/SwitchView.js
index 80ee7198..66950052 100644
--- a/src/ui/web/general/SwitchView.js
+++ b/src/ui/web/general/SwitchView.js
@@ -1,3 +1,5 @@
+import {errorToDOM} from "./error.js";
+
 export class SwitchView {
     constructor(defaultView) {
         this._childView = defaultView;
@@ -23,7 +25,12 @@ export class SwitchView {
         const oldRoot = this.root();
         this._childView.unmount();
         this._childView = newView;
-        const newRoot = this._childView.mount();
+        let newRoot;
+        try {
+            newRoot = this._childView.mount();
+        } catch (err) {
+            newRoot = errorToDOM(err);
+        }
         const parent = oldRoot.parentElement;
         if (parent) {
             parent.replaceChild(newRoot, oldRoot);
diff --git a/src/ui/web/general/error.js b/src/ui/web/general/error.js
new file mode 100644
index 00000000..c218504e
--- /dev/null
+++ b/src/ui/web/general/error.js
@@ -0,0 +1,12 @@
+import {tag} from "./html.js";
+
+export function errorToDOM(error) {
+    const stack = new Error().stack;
+    const callee = stack.split("\n")[1];
+    return tag.div([
+        tag.h2("Something went wrong…"),
+        tag.h3(error.message),
+        tag.p(`This occurred while running ${callee}.`),
+        tag.pre(error.stack),
+    ]);
+}