Expanding on this:

In the original implementation, you call remove_leadspace() without assigning its result to anything. This means that wantarray is undef, so the original implementation of remove_leadspace() returns without doing anything.

Because in Perl there is More Than One Way To Do It, another implementation would be something like:

sub remove_leadspace(
    s/^\s+// for @{ $_[0] };
    return;
}
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This is called by remove_leadspace( $result ). That is, it expects a single argument which is an array reference, modifies the elements of the array (note that the /r qualifier qas removed from the s///), and returns nothing.