connection wasn't properly returned in case of being created

framework/logging/DbTarget.php

@@ -68,14 +68,14 @@ class DbTarget extends Target
 	 */
 	public function getDbConnection()
 	{
-		if ($this->_db !== null) {
+		if ($this->_db === null) {
-			return $this->_db;
-		}
 			$this->_db = \Yii::$application->getComponent($this->connectionID);
 			if (!$this->_db instanceof \yii\db\dao\Connection) {
 				throw new \yii\base\Exception('DbTarget.connectionID must refer to a valid application component ID');
 			}
 		}
+		return $this->_db;
+	}
 
 	/**
 	 * Stores log [[messages]] to DB.