Mark Infer's null dereference in materialize() as a false positive

Infer (ci_infer, also red on develop since #5882) reports a null
dereference in json_sax_dom_parser::null() called from materialize(). The
member pointer the parser stores a value of an object in is set by the
key() before it, so it is not null there.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

include/nlohmann/detail/view/materialize.hpp

@@ -143,6 +143,9 @@ BasicJsonType materialize(const document_data& d, const node* n)
             case value_t::binary:
             case value_t::discarded:
             default:
+                // false positive: a value in an object follows its key(), which set the
+                // member the parser stores it in
+                // @infer-ignore NULLPTR_DEREFERENCE
                 sax.null();
                 break;
         }

single_include/nlohmann/json_view.hpp

@@ -7185,6 +7185,9 @@ BasicJsonType materialize(const document_data& d, const node* n)
             case value_t::binary:
             case value_t::discarded:
             default:
+                // false positive: a value in an object follows its key(), which set the
+                // member the parser stores it in
+                // @infer-ignore NULLPTR_DEREFERENCE
                 sax.null();
                 break;
         }