这个错误通常是由于缺少相关依赖库引起的。可以通过以下步骤解决该问题:
dependencies {
implementation 'com.google.firebase:firebase-firestore:19.2.0'
}
import com.google.firebase.firestore.FirebaseFirestore
val db = FirebaseFirestore.getInstance()
val collectionRef = db.collection("collectionName")