Gatsby で build 時に「A page component must export a React component for it to be valid. Please make sure this file exports a React component:」のエラーがでる
#Gatsby✎ 2021年01月24日Gatsby で build する時に「A page component must export a React component for it to be valid. Please make sure this file exports a React component:」のエラーがでたときの解消法