fix error: lib/review/book/compilable.rb:35:in `basename': no implicit conversion of nil into String (TypeError)
fix error: lib/review/book/compilable.rb:35:in `basename': no implicit conversion of nil into String (TypeError)

takahashim/review,murashitas/review,masawada/review,suzuki/review,kuad9/review_study,suzuki/review,kmuto/review,krororo/review,krororo/review,kuad9/review_study,murashitas/review,takahashim/review,kmuto/review,kmuto/review,krororo/review,masawada/review,orangain/review,orangain/review