I've encountered this error many times. I usually trigger it by forgetting the second half of a fat comma, i.e. using = instead of =>. 
perl -e '%h = (a = 42)'
Can't modify constant item in scalar assignment at -e line 1, near "42
+)
"

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map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

In reply to Re: Problem Declaring a hash by choroba
in thread Problem Declaring a hash by The_Evil_One

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