[liweitianux]

ldns_nsec_bitmap_set_type() and ldns_nsec_bitmap_clear_type() would return false (i.e., LDNS_STATUS_OK) when the input bitmap is NULL.

Following the existing convention, correct it to be LDNS_STATUS_NULL.

[liweitianux]

However, I'm not very sure whether this is the correct/expected fix, i.e., return an error instead of OK for a bitmap=NULL.

I noticed this code mismatch when I was compiling the code in an environment where the true and false are defined as an enumeration, i.e.,

enum { false = 0, true = 1 };

As a result, the compiler generated the following warnings:

.../lib/ldns/dnssec.c: In function ‘ldns_nsec_bitmap_set_type’:
.../lib/ldns/dnssec.c:1444:24: error: implicit conversion from ‘enum <anonymous>’ to ‘ldns_status’ {aka ‘enum ldns_enum_status’} [-Werror=enum-conversion]
 1444 |                 return false;
      |                        ^~~~~
.../lib/ldns/dnssec.c: In function ‘ldns_nsec_bitmap_clear_type’:
.../lib/ldns/dnssec.c:1482:24: error: implicit conversion from ‘enum <anonymous>’ to ‘ldns_status’ {aka ‘enum ldns_enum_status’} [-Werror=enum-conversion]
 1482 |                 return false;
      |                        ^~~~~