From 70b89fbe2f320c7e78dff492727e35dc59c42811 Mon Sep 17 00:00:00 2001
From: Rob Pilling <robpilling@gmail.com>
Date: Tue, 10 Oct 2023 10:50:07 +0100
Subject: [PATCH] backswipe: ignore `undefined` handlers

`undefined` handlers are created when we [remove listeners] part-way
through the array. This fixes `backswipe` for all firmwares, but
leaves the door open for a potential firmware change.

[remove listeners]: https://github.com/bobrippling/Espruino/blob/0f16231a4369bb2d154b9fab5a0d806122cddb39/src/jswrap_object.c#L1035-L1035
---
 apps/backswipe/ChangeLog     | 1 +
 apps/backswipe/boot.js       | 2 +-
 apps/backswipe/metadata.json | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/apps/backswipe/ChangeLog b/apps/backswipe/ChangeLog
index 1e5479d6e..54ffebfc7 100644
--- a/apps/backswipe/ChangeLog
+++ b/apps/backswipe/ChangeLog
@@ -1,2 +1,3 @@
 0.01: New App!
 0.02: Don't fire if the app uses swipes already.
+0.03: Only count defined handlers in the handler array.
diff --git a/apps/backswipe/boot.js b/apps/backswipe/boot.js
index e46f902eb..d5d54cd59 100644
--- a/apps/backswipe/boot.js
+++ b/apps/backswipe/boot.js
@@ -26,7 +26,7 @@
     if (Bangle["#on"+eventType] === undefined) {
       return 0;
     } else if (Bangle["#on"+eventType] instanceof Array) {
-      return Bangle["#on"+eventType].length;
+      return Bangle["#on"+eventType].filter(x=>x).length;
     } else if (Bangle["#on"+eventType] !== undefined) {
       return 1;
     }
diff --git a/apps/backswipe/metadata.json b/apps/backswipe/metadata.json
index c7cb2185f..add609a0f 100644
--- a/apps/backswipe/metadata.json
+++ b/apps/backswipe/metadata.json
@@ -1,7 +1,7 @@
 { "id": "backswipe",
   "name": "Back Swipe",
   "shortName":"BackSwipe",
-  "version":"0.02",
+  "version":"0.03",
   "description": "Service that allows you to use an app's back button using left to right swipe gesture",
   "icon": "app.png",
   "tags": "back,gesture,swipe",