You're using the g option on the match operator when you don't mean to do so. m//g acts as an iterator in scalar context.

$_ = 'abc';
print /(.)/g ? $1 : '[]', "\n";  # a
print /(.)/g ? $1 : '[]', "\n";  # b
print /(.)/g ? $1 : '[]', "\n";  # c
print /(.)/g ? $1 : '[]', "\n";  # []
print /(.)/g ? $1 : '[]', "\n";  # a
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$_ = 'abc';
print /(.)/ ? $1 : '[]', "\n";  # a
print /(.)/ ? $1 : '[]', "\n";  # a
print /(.)/ ? $1 : '[]', "\n";  # a
print /(.)/ ? $1 : '[]', "\n";  # a
print /(.)/ ? $1 : '[]', "\n";  # a
[download]