KRE throws error - unresolved compilation problems

Katalon Runtime Engine throws following error but Katalon Studio 7.8.2 doesn’t throw any errors when calling custom keywords and executing test cases or test suite -

ERROR k.k.c.m.CustomKeywordDelegatingMetaClass - ? Unresolved compilation problems:

                Groovy:unable to resolve class MobileBuiltInKeywords

                Groovy:unable to resolve class WSBuiltInKeywords

                Groovy:unable to resolve class WebUiBuiltInKeywords

This issue got resolved after removing unused imports from the custom keyword groovy script. I will continue to keep an eye in case this issue of Katalon Runtime Engine recurs.