Simple examples of where this code fails:

my $line = '1|firstname|last, name"|address1|city|state|zip';
my $line = '1|firstname|last, name|address1|city|"state,"|zip';
my $line = '1|firstname|last, name|,",address1|city|state|zip';
my $line = '1|firstname|,"|last, name|address1|city|state|zip';
my $line = "1|firstname|last, name|,\n"address1"|city|state|zip";
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and so on.