What does the error message "Given String is empty or null" mean in Firebase and why am I encountering it?

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The error message "Given String is empty or null" in Firebase means that you are trying to pass an empty or null value to a method or function that expects a non-empty string parameter. This error often occurs when you are trying to set a value in the Firebase Realtime Database or Firestore with an empty or null key or field name. To resolve this error, you should make sure that all the values you are passing to Firebase methods are non-empty strings.