
As seen in the screenshot, the error message tells the user that no field to update is specified, instead of the error being regarding the invalid index. Whilst I agree that there being no field to update is also a valid error, I believe when no flags are specified and index is invalid/ missing, the error message should be focused upon the index first and foremost.
As seen below, even if I omit the index entirely, the same error message appears. Then, following the error message and adding in the field, I am finally presented with the respective index format error.

Also, it would be good to indicate to enter the index before any flags, since this is absent from help --update. If i then enter an index after the fields to be changed, the error message should be flagging up the command format being incorrect instead of the index not being in range.

As seen in the screenshot, the error message tells the user that no field to update is specified, instead of the error being regarding the invalid index. Whilst I agree that there being no field to update is also a valid error, I believe when no flags are specified and index is invalid/ missing, the error message should be focused upon the index first and foremost.
As seen below, even if I omit the index entirely, the same error message appears. Then, following the error message and adding in the field, I am finally presented with the respective index format error.
Also, it would be good to indicate to enter the index before any flags, since this is absent from help --update. If i then enter an index after the fields to be changed, the error message should be flagging up the command format being incorrect instead of the index not being in range.