input: Write a python function to read data from an Excel spreadsheet using Python's xlrd library. The function should read in the spreadsheet, open the first sheet, and then iterate over each row, reading the data and storing it in a list. Handle any errors that may arise.
  assert read_excel_data('test.xlsx')==[['Header1', 'Header2'], ['Row1Col1', 'Row1Col2'], ['Row2Col1', 'Row2Col2']]
  assert read_excel_data('empty.xlsx')==[]
output: def read_excel_data(file_path):
      import xlrd
  
      data = []
  
      try:
          workbook = xlrd.open_workbook(file_path)
          sheet = workbook.sheet_by_index(0)
  
          for row_idx in range(sheet.nrows):
              row_data = sheet.row_values(row_idx)
              data.append(row_data)
      except Exception as e:
          print(f"An error occurred: {e}")
  
      return data