Where you have:

use v5.12;
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"Similarly, if the specified Perl version is greater than or equal to 5.12.0, strictures are enabled lexically as with use strict."(https://perldoc.pl/functions/use).

So to fix your code, use my:

while ( my ($key, $value) = each %count) {
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Returns:

pebbles => 1
dino => 1
wlima => 1
fred => 3
barney => 2
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