void checkState() {
    if (mError != null) {
      return;
    }
    for (int i = 0; i < mTiling.getWidth(); i++) {
      for (int j = 0; j < mTiling.getHeight(); j++) {
        if (mTiling.getAt(i, j) == null) {
          throw new IllegalStateException("expected all tiles to be filled");
        }
      }
    }
  }
Sanity checks that the record is ready to be persisted
core/src/main/java/com/facebook/testing/screenshot/internal/RecordBuilderImpl.java