From 4bb20823fe5f7283336a4837e1999730b85ad4d9 Mon Sep 17 00:00:00 2001
From: Andrea Leopardi <an.leopardi@gmail.com>
Date: Mon, 15 Sep 2025 10:23:11 +0200
Subject: [PATCH 1/3] Fix safe JSON encoding of improper lists

---
 lib/sentry/client.ex        | 26 +++++++++++++++-----------
 test/sentry/client_test.exs |  4 +++-
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/lib/sentry/client.ex b/lib/sentry/client.ex
index dc924bd8..98b06191 100644
--- a/lib/sentry/client.ex
+++ b/lib/sentry/client.ex
@@ -361,18 +361,22 @@ defmodule Sentry.Client do
   end
 
   defp sanitize_non_jsonable_value(value, json_library) when is_list(value) do
-    {mapped, changed?} =
-      Enum.map_reduce(value, _changed? = false, fn value, changed? ->
-        case sanitize_non_jsonable_value(value, json_library) do
-          :unchanged -> {value, changed?}
-          {:changed, value} -> {value, true}
-        end
-      end)
-
-    if changed? do
-      {:changed, mapped}
+    if List.improper?(value) do
+      {:changed, inspect(value)}
     else
-      :unchanged
+      {mapped, changed?} =
+        Enum.map_reduce(value, _changed? = false, fn value, changed? ->
+          case sanitize_non_jsonable_value(value, json_library) do
+            :unchanged -> {value, changed?}
+            {:changed, value} -> {value, true}
+          end
+        end)
+
+      if changed? do
+        {:changed, mapped}
+      else
+        :unchanged
+      end
     end
   end
 
diff --git a/test/sentry/client_test.exs b/test/sentry/client_test.exs
index 70e7a9bb..74b38e47 100644
--- a/test/sentry/client_test.exs
+++ b/test/sentry/client_test.exs
@@ -61,7 +61,8 @@ defmodule Sentry.ClientTest do
             bool: true,
             null: nil,
             int: 2,
-            map: %{bool: false}
+            map: %{bool: false},
+            improper_list: [1 | 2]
           },
           user: %{id: "valid-ID", email: {"user", "@example.com"}},
           tags: %{valid: "yes", tokens: MapSet.new([1])},
@@ -78,6 +79,7 @@ defmodule Sentry.ClientTest do
       assert rendered.extra.null == nil
       assert rendered.extra.int == 2
       assert rendered.extra.map.bool == false
+      assert rendered.extra.improper_list == "[1 | 2]"
 
       assert rendered.user.id == "valid-ID"
       assert rendered.user.email == ~s({"user", "@example.com"})

From 342cd00c33854ddfa057d98d84e20312dece5414 Mon Sep 17 00:00:00 2001
From: Andrea Leopardi <an.leopardi@gmail.com>
Date: Thu, 18 Sep 2025 13:05:41 +0200
Subject: [PATCH 2/3] FIXUP

---
 CHANGELOG.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 54b3de07..4a374bd4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## 11.0.4
+
+### Bug fixes
+
+- Correctly sanitize improper lists in Sentry context (attached to any event).
+
 ## 11.0.3
 
 #### Various improvements

From 69fa1f0208d3a09ac85743a0676bafb8a8a27725 Mon Sep 17 00:00:00 2001
From: Andrea Leopardi <an.leopardi@gmail.com>
Date: Thu, 18 Sep 2025 13:47:42 +0200
Subject: [PATCH 3/3] FIXUP

---
 CHANGELOG.md | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4a374bd4..2751acde 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,6 @@
-## 11.0.4
+## Unreleased
 
-### Bug fixes
-
-- Correctly sanitize improper lists in Sentry context (attached to any event).
+- Fix safe JSON encoding of improper lists ([#938](https://github.com/getsentry/sentry-elixir/pull/938))
 
 ## 11.0.3