Fix error pages in multilang

src/Cms/Language.php

@@ -8,6 +8,7 @@
 use Kirby\Exception\LogicException;
 use Kirby\Exception\PermissionException;
 use Kirby\Filesystem\F;
+use Kirby\Toolkit\A;
 use Kirby\Toolkit\Locale;
 use Kirby\Toolkit\Str;
 use Throwable;
@@ -213,7 +214,7 @@ public static function create(array $props): static
 	 */
 	public function delete(): bool
 	{
-		$kirby = App::instance();
+		$kirby = $this->kirby();
 		$user  = $kirby->user();
 		$code  = $this->code();
 
@@ -382,7 +383,20 @@ public function pattern(): string
 		$path = $this->path();
 
 		if (empty($path) === true) {
-			return '(:all)';
+			$pattern = '(:all)';
+
+			// match anything except paths that begin with the prefix
+			// of any other language
+			$languages = $this->kirby()->languages()->not($this)->values(
+				fn ($language) => $language->path()
+			);
+
+			if (count($languages) > 0) {
+				$pattern = '^(?!(?:' . A::join($languages, '|') . ')\/)' . $pattern;
+			}
+
+
+			return $pattern;
 		}
 
 		return $path . '/(:all?)';

tests/Cms/Languages/LanguageRoutesTest.php

@@ -7,6 +7,7 @@
 class LanguageRoutesTest extends TestCase
 {
 	protected $app;
+	public const FIXTURES = __DIR__ . '/fixtures';
 
 	public function setUp(): void
 	{
@@ -37,6 +38,19 @@ public function setUp(): void
 	public function testFallback()
 	{
 		$app = $this->app->clone([
+			'languages' => [
+				[
+					'code'    => 'fr',
+					'name'    => 'French',
+					'default' => true,
+					'url'     => '/',
+				],
+				[
+					'code'    => 'en',
+					'name'    => 'English',
+					'url'     => '/en',
+				],
+			],
 			'site' => [
 				'children' => [
 					[
@@ -48,10 +62,56 @@ public function testFallback()
 		]);
 
 		$app->call('notes');
+		$this->assertSame($app->language()->code(), 'fr');
+
+		$app->call('en/notes');
 		$this->assertSame($app->language()->code(), 'en');
+	}
+
+	public static function languagePrefixProvider(): array {
+		return [
+			['not-exists', 'Erreur'],
+			['en/not-exists', 'Error']
+		];
+	}
+
+	/**
+	 * @dataProvider languagePrefixProvider
+	 */
+	public function testLanguagePrefix($path, $body)
+	{
+		$app = new App([
+			'roots' => [
+				'index'     => static::FIXTURES,
+				'languages' => static::FIXTURES . '/languages',
+				'templates' => static::FIXTURES . '/templates'
+			],
+			'site' => [
+				'children' => [
+					[
+						'slug'     	   => 'error',
+						'template' 	   => 'error',
+						'translations' => [
+							[
+								'code'    => 'fr',
+								'content' => [
+									'title' => 'Erreur'
+								]
+							],
+							[
+								'code'    => 'en',
+								'content' => [
+									'title' => 'Error'
+								]
+							]
+						]
+					]
+				]
+			]
+		]);
+
 
-		$app->call('de/notes');
-		$this->assertSame($app->language()->code(), 'de');
+		$this->assertSame($body, $app->render($path)->body());
 	}
 
 	public function testNotNextWhenFalsyReturn()

tests/Cms/Languages/LanguageTest.php

@@ -556,6 +556,33 @@ public function testPattern($input, $expected)
 		$this->assertSame($expected, $language->pattern());
 	}
 
+	/**
+	 * @covers ::pattern
+	 */
+	public function testPatternWithNoPathPrefixButOtherLanguages()
+	{
+		$app = $this->app->clone([
+			'languages' => [
+				[
+					'code'    => 'en',
+					'name'    => 'English',
+					'default' => true,
+					'url'     => '/'
+				],
+				[
+					'code' => 'de',
+					'name' => 'Deutsch',
+				],
+				[
+					'code' => 'fr',
+					'name' => 'Frances',
+				]
+			]
+		]);
+
+		$this->assertSame('^(?!(?:de|fr)\/)(:all)', $app->language('en')->pattern());
+	}
+
 	/**
 	 * @covers ::root
 	 */

tests/Cms/Languages/fixtures/languages/en.php

@@ -0,0 +1,15 @@
+<?php
+
+return [
+    'code' => 'en',
+    'default' => false,
+    'direction' => 'ltr',
+    'locale' => [
+        'LC_ALL' => 'en_US'
+    ],
+    'name' => 'English',
+    'translations' => [
+
+    ],
+    'url' => NULL
+];

tests/Cms/Languages/fixtures/languages/fr.php

@@ -0,0 +1,15 @@
+<?php
+
+return [
+    'code' => 'fr',
+    'default' => true,
+    'direction' => 'ltr',
+    'locale' => [
+        'LC_ALL' => 'fr_FR'
+    ],
+    'name' => 'French',
+    'translations' => [
+
+    ],
+    'url' => '/'
+];

tests/Cms/Languages/fixtures/templates/default.php

@@ -0,0 +1 @@
+<?= $page->title();