RubyMine: expected; or end of line after some colon

My rails project works fine. But rubimine highlights an error expected ; or end of line

after some colon :

. for example

before_action :set_answer, only: [:show, :edit, :update, :destroy]
format.html { redirect_to @answer, notice: 'Answer was successfully created.' }

      

        
        
        
      

    

In the above ruby, an error stands out after only:

and notice:

. But it doesn't highlight the error after :set_answer, :show, :edit, :update or :destroy

.

What is the reason for this and how can I fix it?