$scalar, $array[$index] and $hash{$key} always evaluate to a scalar. Should the variable or element not exist, that scalar is undef.

$ perl -le'@x = $scalar;    print 0+@x; print $x[0] // "[undef]"'
1
[undef]

$ perl -le'@x = $array[0];  print 0+@x; print $x[0] // "[undef]"'
1
[undef]

$ perl -le'@x = $hash{foo}; print 0+@x; print $x[0] // "[undef]"'
1
[undef]
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