From 9fd067c6e33e0956d90988e19424b8bdefdcd586 Mon Sep 17 00:00:00 2001
From: tophf <tophf@gmx.com>
Date: Tue, 21 Mar 2017 00:35:51 +0300
Subject: [PATCH] Switch editor to add style mode when id=nonexistentstyle

---
 edit.js    | 6 +++++-
 storage.js | 8 ++++++--
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/edit.js b/edit.js
index f948ecbb..a17fabdb 100644
--- a/edit.js
+++ b/edit.js
@@ -1087,7 +1087,11 @@ function init() {
 	// This is an edit
 	tE("heading", "editStyleHeading", null, false);
 	getStylesSafe({id: params.id}).then(styles => {
-		const style = styles[0];
+		let style = styles[0];
+		if (!style) {
+			style = {id: null, sections: []};
+			history.replaceState({}, document.title, location.pathname);
+		}
 		styleId = style.id;
 		setStyleMeta(style);
 		onload = () => {
diff --git a/storage.js b/storage.js
index 1696ad1e..9d7fd5cd 100644
--- a/storage.js
+++ b/storage.js
@@ -182,9 +182,13 @@ function filterStyles(options = {}) {
 
 	const styles = id == null
 		? (code ? cachedStyles.list : cachedStyles.noCode)
-		: [code ? cachedStyles.byId.get(id).style : cachedStyles.byId.get(id).noCode];
+		: [(cachedStyles.byId.get(id) || {})[code ? 'style' : 'noCode']];
 	const filtered = asHash ? {} : [];
-
+	if (!styles) {
+		// may happen when users [accidentally] reopen an old URL
+		// of edit.html with a non-existent style id parameter
+		return filtered;
+	}
 	for (let i = 0, style; (style = styles[i]); i++) {
 		if ((enabled == null || style.enabled == enabled)
 			&& (url == null || style.url == url)