Here's the script:

    #!/usr/bin/perl 
    use strict; 

    ++$a{$x}; 

and when run, produces,

    Global symbol "%a" requires explicit package name at ./test3.pl line 4.
    Global symbol "$x" requires explicit package name at ./test3.pl line 4.

So, I'm not sure if I see that point. Are you not a fan of autovivification? Because it: rules. I think the only thing one has to understand is the use of exists(), to see if there is, say, a key in a hash, rather than defined():

    #!/usr/bin/perl 
    use strict; 

    my %foo = (batz => undef); 

    for (qw(bar batz)){ 
        if(exists($foo{$_})){ 
            print "$_ exists!\n"; 
            if(defined($foo{$_})){ 
                print "and $_ is defined.\n"; 
            }
            else { 
                print "and $_ is undefined.\n"; 
            }
        }
        else { 
            print "$_ doesn't actually exist\n"; 
    
        }
    }

prints,

    bar doesn't actually exist
    batz exists!
    and batz is undefined.