fix(nullcache): make get compliant with the interface

The interface defines ICacheEntry|false, thus we should not return null.

Signed-off-by: Daniel Kesselberg <mail@danielkesselberg.de>

build/psalm-baseline.xml

@@ -4112,31 +4112,12 @@
     </InvalidOperand>
   </file>
   <file src="lib/private/Lockdown/Filesystem/NullCache.php">
-    <InvalidNullableReturnType>
-      <code><![CDATA[get]]></code>
-    </InvalidNullableReturnType>
     <InvalidReturnStatement>
       <code><![CDATA[[]]]></code>
     </InvalidReturnStatement>
     <InvalidReturnType>
       <code><![CDATA[getIncomplete]]></code>
     </InvalidReturnType>
-    <NullableReturnStatement>
-      <code><![CDATA[$file !== '' ? null :
-			new CacheEntry([
-				'fileid' => -1,
-				'parent' => -1,
-				'name' => '',
-				'path' => '',
-				'size' => '0',
-				'mtime' => time(),
-				'storage_mtime' => time(),
-				'etag' => '',
-				'mimetype' => FileInfo::MIMETYPE_FOLDER,
-				'mimepart' => 'httpd',
-				'permissions' => Constants::PERMISSION_READ
-			])]]></code>
-    </NullableReturnStatement>
   </file>
   <file src="lib/private/Lockdown/Filesystem/NullStorage.php">
     <TooManyArguments>

lib/private/Lockdown/Filesystem/NullCache.php

@@ -21,20 +21,23 @@ class NullCache implements ICache {
 	}
 
 	public function get($file) {
-		return $file !== '' ? null :
-			new CacheEntry([
-				'fileid' => -1,
-				'parent' => -1,
-				'name' => '',
-				'path' => '',
-				'size' => '0',
-				'mtime' => time(),
-				'storage_mtime' => time(),
-				'etag' => '',
-				'mimetype' => FileInfo::MIMETYPE_FOLDER,
-				'mimepart' => 'httpd',
-				'permissions' => Constants::PERMISSION_READ
-			]);
+		if ($file !== '') {
+			return false;
+		}
+
+		return 	new CacheEntry([
+			'fileid' => -1,
+			'parent' => -1,
+			'name' => '',
+			'path' => '',
+			'size' => '0',
+			'mtime' => time(),
+			'storage_mtime' => time(),
+			'etag' => '',
+			'mimetype' => FileInfo::MIMETYPE_FOLDER,
+			'mimepart' => 'httpd',
+			'permissions' => Constants::PERMISSION_READ
+		]);
 	}
 
 	public function getFolderContents($folder) {

tests/lib/Lockdown/Filesystem/NullCacheTest.php

@@ -27,7 +27,7 @@ class NulLCacheTest extends \Test\TestCase {
 	}
 
 	public function testGetEmpty(): void {
-		$this->assertNull($this->cache->get('foo'));
+		$this->assertFalse($this->cache->get('foo'));
 	}
 
 	public function testGet(): void {