Name "main::x" used only once: possible typo at t/22-diagfile.pl line 3 (#1)
    [./dummy.txt]
    This is a dummy message for the used only once warning.
    [perl]
    (W once) Typographical errors often show up as unique variable names.
    If you had a good reason for having a unique name, then just mention it
    again somehow to suppress the message.  The our declaration is
    provided for this purpose.
    
Use of uninitialized value in division (/) at t/22-diagfile.pl line 3 (#2)
    [perl]
    (W uninitialized) An undefined value was used as if it were already
    defined.  It was interpreted as a "" or a 0, but maybe it was a mistake.
    To suppress this warning assign a defined value to your variables.
    
    To help you figure out what was undefined, perl tells you what operation
    you used the undefined value in.  Note, however, that perl optimizes your
    program and the operation displayed in the warning may not necessarily
    appear literally in your program.  For example, "that $foo" is
    usually optimized into "that " . $foo, and the warning will refer to
    the concatenation (.) operator, even though there is no . in your
    program.
    
Illegal division by zero at t/22-diagfile.pl line 3 (#3)
    [./dummy.txt]
    This is a dummy message for the division by zero.
    
    [perl]
    (F) You tried to divide a number by 0.  Either something was wrong in
    your logic, or you need to put a conditional in to guard against
    meaningless input.
    
Uncaught exception from user code:
	Illegal division by zero at t/22-diagfile.pl line 3.