You posted several hundreds of lines of code without including the input files and indication of what we should enter at the input() prompts . You also failed to include a complete copy of the error message so we do not know which line the message was on or which variables were involved . We can only make guesses as to the cause of the problem .
What I notice is that you use importdata and that in the btext case you use dot indexing of the result to access the textdata field. However importdata does not necessarily return a struct for txt files .
My recommendation is to never use importdata . The output it produces is too inconsistent .
