Hi Shikha,
I guess from the current fcc configuration, why it is not raising issue even though there is blank line is because it is considering from the beginning of the blank line to the end of 789 as single field.
If you are using fieldfixedlength, then in that case it might have thrown error but since you are using fieldseparator, until it faces the separator it is considering the entire as single field value rather than what it means.
So, my suggestion is to try with the below approach.