From 38f8858426d63b283ae20131e82a9ad7dab3c8a9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krystian=20Droz=CC=87dz=CC=87yn=CC=81ski?=
 <krystian@drozdzynski.me>
Date: Thu, 24 Oct 2024 17:25:06 +0200
Subject: [PATCH] Fix `DefaultTheme` interface

---
 .changeset/two-mangos-attack.md  | 5 +++++
 packages/core/src/constructor.ts | 6 ++++--
 2 files changed, 9 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/two-mangos-attack.md

diff --git a/.changeset/two-mangos-attack.md b/.changeset/two-mangos-attack.md
new file mode 100644
index 0000000..0b05d3e
--- /dev/null
+++ b/.changeset/two-mangos-attack.md
@@ -0,0 +1,5 @@
+---
+"@teiler/core": patch
+---
+
+Fix `DefaultTheme` interface
diff --git a/packages/core/src/constructor.ts b/packages/core/src/constructor.ts
index b0893af..efdada6 100644
--- a/packages/core/src/constructor.ts
+++ b/packages/core/src/constructor.ts
@@ -5,14 +5,16 @@ import type { Pattern } from './pattern'
 import hash from './hash'
 import { compile, transpile } from './css'
 
-type DefaultTheme = {}
+interface DefaultTheme {
+  [key: string]: unknown
+}
 
 type Arguments<Props> = {
   theme: DefaultTheme
 } & Props
 
 type CSS<Props> = { styles: Style<Props>[]; id: string; __css__: true }
-type Expression<Props> = (props: Arguments<Props>) => string | boolean | CSS<Props>
+type Expression<Props> = (props: Arguments<Props>) => string | boolean | undefined | CSS<Props>
 type Raw = string | number
 type Properties<Props> = Expression<Props> | StyleDefinition<HTMLElements, Props> | Pattern<HTMLElements, Props> | TeilerComponent<HTMLElements, Props> | Raw
 type Style<Props> = [string[], Properties<Props>[]]