Updated CHANGELOG.md file

Author: bohdan-harniuk

CHANGELOG.md

@@ -20,6 +20,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0).
 
 ### Fixed
 
+- Fixed NullPointerException at ObserverDeclarationInspection.java:188 [#1143](https://github.com/magento/magento2-phpstorm-plugin/issues/1143)
 - Fixed IncorrectOperationException: Rebind cannot be performed for class PolyVariantReferenceBase [#1173](https://github.com/magento/magento2-phpstorm-plugin/pull/1173)
 - Fixed create an observer for an event doesn't work through the context menu [#1166](https://github.com/magento/magento2-phpstorm-plugin/pull/1166)
 - Fixed IOException: Invalid file name at ReportBuilder [#1154](https://github.com/magento/magento2-phpstorm-plugin/pull/1154)