Revert default password setting & using "HiddenString" even for empty strings

config/defaults.config.php

@@ -22,7 +22,7 @@ return [
 
 		// pass (String)
 		// Database user password. Please don't use empty passwords.
-		'password' => new \ParagonIE\HiddenString\HiddenString(''),
+		'password' => '',
 
 		// base (String)
 		// Database name.

src/Core/Config/Cache/ConfigCache.php

@@ -95,7 +95,7 @@ class ConfigCache implements IConfigCache, IPConfigCache
 
 		if ($this->hidePasswordOutput &&
 		    $key == 'password' &&
-		    !empty($value) && is_string($value)) {
+		    is_string($value)) {
 			$this->config[$cat][$key] = new HiddenString((string) $value);
 		} else {
 			$this->config[$cat][$key] = $value;

tests/src/Core/Config/Cache/ConfigCacheTest.php

@@ -4,6 +4,7 @@ namespace Friendica\Test\src\Core\Config\Cache;
 
 use Friendica\Core\Config\Cache\ConfigCache;
 use Friendica\Test\MockedTest;
+use ParagonIE\HiddenString\HiddenString;
 
 class ConfigCacheTest extends MockedTest
 {
@@ -322,7 +323,8 @@ class ConfigCacheTest extends MockedTest
 			]
 		]);
 
-		$this->assertEmpty($configCache->get('database', 'password'));
+		$this->assertNotEmpty($configCache->get('database', 'password'));
+		$this->assertInstanceOf(HiddenString::class, $configCache->get('database', 'password'));
 		$this->assertEmpty($configCache->get('database', 'username'));
 	}