Problem with awk getline and reading file in nest if statements

Question

Before I added the else if/else, when i only just had the:
if (/Easy: /) .. part

The program would launch when I put awk -f oscp-notes.awk and then put input, &c.
It would then print out appropriate Easy machines; however, after I added the else if section.
It will not print either easy or medium machines now. I do not have any errors. I figured that I needed to close(file) so I could re-read. I am stuck. I would like to be able to read/close and make rest of conditional statements to include user input whether it is easy/medium/hard/insane. Is this possible?

Edit: I have also tried close(file) instead of close("TJnulls.txt").

BEGIN { 
    printf "Please select a chapter by entering chapter number: "
    getline entry < "-"
    $2 == entry
    file = "TJnulls.txt"

Test if statement

    if (entry == 2) {
        printf "Please select difficulty (easy, medium, hard, insane): "
        getline difficulty < "-"
        $3 == difficulty
        if (difficulty == easy) {
            {print "\n"}
            {print "Obtaining the list of easy machines:\n"}
            while (( getline<file) > 0) {
            if (/Easy: /) {
                {print $2};
            } else {
                close("TJnulls.txt");
                break;
            }
            }
        } else if (difficulty == medium) {
            {print "\n"}
            {print "Obtaining the list of medium machines:\n"}
            while ( ( getline<file) > 0) {
            if (/Medium: /)
                {print $2}
            }
        }
     }
}

EDIT: I have tried doing the following:
Use a for loop, with if conditions to a for loop and if conditions.

BEGIN {
printf "Please select a chapter by entering chapter number: "
getline entry < "-"
# For loop
i = 0;
{
   for (i=1; i <= 11; i++) {
       if ( ( entry == i ) &&
          ( i == 2 ) )
           file = "TJnulls.txt"
           {print "\nPlease select a difficulty:\n (easy=1, medium=2, hard=3, insane=4, menu=0)\n"}
           getline difficulty < "-"
           x = 0;
           for (x=1; x <= 4; x++) {
               if ( ( difficulty == x ) &&
                  ( x == 1 ) )
                   file = "TJnulls.txt"
                   while ( (getline<file) > 0 ) {
                   if (/Easy: /)
                       {print $2}
                   }
               if ( ( difficulty == i ) &&
                  ( x == 2 ) )
                   file2 = "TJnulls.txt"
                   while ( (getline<file2) > 0 ) {
                   if (/Medium: /)
                       {print $2}
                   }
           }
   }
}
}

The problem is that it gives me an error:
18: fatal: expression for `<' redirection has null string value
Also, when I removed the file - variable (the first one) it would bark at me.

Answer 1

I found a fix that works. I believe it was a problem with a bracket {.

  BEGIN {
  # prompts user
  # user makes selection for chapter by entering a number 1-11
  {print "Please select a chapter by entering a number: "}
  getline entry < "-"

  # initializing f_1
  f_1 = 0;
  for ( f_1 = 1; f_1 <= 11; f_1++) {
      # if conditional statement if user selects chapter 2: TJ nulls list.
      # prompt user to select difficulty of machine.
      # future updates consider making entering text easy and converting into a number in the background
      if ( ( entry == f_1 ) && ( f_1 == 2 ) ) {
          {print "\nPlease select a difficulty: easy=1, medium=2, hard=3, insane=4, return=0"}
          getline difficulty < "-"

          # initializing f_2
          f_2 = 0;
          for ( f_2 = 1; f_2 <= 4; f_2++ ) {
              if ( ( difficulty == f_2 ) && ( f_2 == 1 ) ) {
                  {print "\nObtaining list of easy machines:\n" dash}
                  while ( ( getline<file02 ) >0 ) {
                  if (/Easy: /)
                      {print $2}
                  }
              }
              if ( ( difficulty == f_2 ) && ( f_2 == 2 ) ) {
                  {print "\nObtaining list of medium machines:\n" dash}
                  while ( ( getline<file02 ) >0 ) {
                  if (/Medium: /)
                      {print $2}
                  }
              }
          }
      }
  }

}