const [alertState, setAlertState] = useState(false);
  const onChange = (e) => {
    if (e.target.value < 0) setAlertState(true)
  }
 <>
  <StyledTableCell align="center">
    <TextField
      inputRef={register({ required: true })}
      inputProps={{ min: 0 }}
      type="number"
      error={error}
      variant="outlined"
    />
  </StyledTableCell>
  <StyledTableCell align="center">
    <TextField
      inputRef={register({ required: true })}
      inputProps={{ min: 0 }}
      type="number"
      error={error2}
      variant="outlined"
    />
  </StyledTableCell>
  <StyledTableCell align="center">
    <TextField
      inputRef={register({ required: true })}
      inputProps={{ readOnly: true }}
      type="number"
      onChange={onChange}
      value={fields[row.meta_label_id].plan - fields[row.meta_label_id].fact}
    />
  </StyledTableCell>
</>;

const [alertState, setAlertState] = useState(false);
  const onChange = (e) => {
    if (e.target.value < 0) setAlertState(true)
  }
 <>
  <StyledTableCell align="center">
    <TextField
      inputRef={register({ required: true })}
      inputProps={{ min: 0 }}
      type="number"
      error={error}
      variant="outlined"
    />
  </StyledTableCell>
  <StyledTableCell align="center">
    <TextField
      inputRef={register({ required: true })}
      inputProps={{ min: 0 }}
      type="number"
      error={error2}
      variant="outlined"
    />
  </StyledTableCell>
  <StyledTableCell align="center">
    <TextField
      inputRef={register({ required: true })}
      inputProps={{ readOnly: true }}
      type="number"
      onChange={onChange}
      value={fields[row.meta_label_id].plan - fields[row.meta_label_id].fact}
    />
  </StyledTableCell>
</>;

const fields = watch();