When receiveImage() tries to write into the txt files, this error occurs:

An error occurred.
java.io.FileNotFoundException: imageWithError.txt (Δεν ήταν δυνατή η προσπέλαση του αρχείου από τη διεργασία, επειδή χρησιμοποιείται ήδη από κάποια άλλη διεργασία)
at java.base/java.io.FileOutputStream.open0(Native Method)
at java.base/java.io.FileOutputStream.open(FileOutputStream.java:291)
at java.base/java.io.FileOutputStream.(FileOutputStream.java:234)
at java.base/java.io.FileOutputStream.(FileOutputStream.java:155)
at java.base/java.io.FileWriter.(FileWriter.java:82)
at userApp.writeToFile(userApp.java:95)
at userApp.receiveImage(userApp.java:170)
at userApp.demo(userApp.java:220)
at userApp.main(userApp.java:19)

However, the program continues execution and does create the txt files correctly. The jpeg files have no problem.
I can just comment out the txt files part since we no longer need it anyway, but it would be nice to know the reason behind this.