Maybe final version

program Project2;
{$APPTYPE CONSOLE}
uses
   System.SysUtils;
const
   ErrorMessage = 'Error! Enter name (nonempty string, starts with uppercase letter)';
var
   IsInvalid, HasAllLetters : Boolean;
   Alphabet : set of 'A'..'z';
   Name : String;
   i : Integer;
begin
   Alphabet  := ['A'..'z'];
   IsInvalid := True;
   Writeln('This program can recognize and greet one of 5 friends');
   while IsInvalid do
      try
         HasAllLetters := True;
         Writeln('Enter your shortened name');
         Readln(Name);
         if Name <> '' then
         begin
            for i := 1 to Length(Name) do
               if not (Name[i] in Alphabet) then
                  HasAllLetters := False;

            if HasAllLetters then
               IsInvalid := False
            else
               Writeln(ErrorMessage)
         end
         else
            Writeln(ErrorMessage);
      except
         Writeln(ErrorMessage);
      end;
   if Name = 'Lynn' then
      Writeln('Hello Carolyn!')
   else
      if Name = 'Mike' then
         Writeln('Hello Michael!')
      else
         if Name = 'Bob' then
            Writeln('Hello Robert!')
         else
            if Name = 'Liz' then
               Writeln('Hello Elizabeth!')
            else
               if Name = 'Peg' then
                  Writeln('Hello Margareth!')
               else
                  Writeln('I DON''T KNOW YOU!');
   Readln;
end.