2 tests assert and fail with Illegal instruction error

Debug trace:

Program received signal SIGILL, Illegal instruction.
Privileged opcode.
std::__1::basic_string_view<char, std::__1::char_traits<char> >::remove_prefix[abi:se190107](unsigned long) (this=0x7fffffffd798, __n=18446744073709551615)
    at /usr/include/c++/v1/string_view:421
421         _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__n <= size(), "remove_prefix() can't remove more than size()");
(gdb) bt
#0  std::__1::basic_string_view<char, std::__1::char_traits<char> >::remove_prefix[abi:se190107](unsigned long) (this=0x7fffffffd798, __n=18446744073709551615)
    at /usr/include/c++/v1/string_view:421
#1  0x000000000020f8dd in camp::experimental::insertArgsString<std::__1::tuple<int&>, 0ul>(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, std::__1::basi
c_string_view<char, std::__1::char_traits<char> >, std::__1::tuple<int&>&&, std::__1::integer_sequence<unsigned long, 0ul>)::{lambda(auto:1&&)#1}::operator()<int&>(std
::__1::tuple<int&>&&) (this=0x7fffffffd780, arg=@0x7fffffffda8c: 7) at /usr/ports/devel/camp/work/camp-2025.09.0/include/camp/helpers.hpp:404
#2  0x000000000020c728 in camp::experimental::insertArgsString<std::__1::tuple<int&>, 0ul> (str=..., arg_names=..., args_tuple=...)
    at /usr/ports/devel/camp/work/camp-2025.09.0/include/camp/helpers.hpp:410
#3  0x000000000020a7fe in CampErrors_InsertArgsString_Test::TestBody (this=0x2c82d010) at /usr/ports/devel/camp/work/camp-2025.09.0/test/errors.cpp:143
#4  0x000000002bf34c54 in testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void> (object=0x2c82d010,
    method=&virtual testing::Test::TestBody(), location=0x2beabbed "the test body")
    at /usr/ports/devel/camp/work/camp-2025.09.0/extern/blt/thirdparty_builtin/googletest/googletest/src/gtest.cc:2621
#5  0x000000002bf0c434 in testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void> (object=0x2c82d010, method=&virtual testing::Test::TestBody(),
    location=0x2beabbed "the test body") at /usr/ports/devel/camp/work/camp-2025.09.0/extern/blt/thirdparty_builtin/googletest/googletest/src/gtest.cc:2657
#6  0x000000002beebe97 in testing::Test::Run (this=0x2c82d010)
    at /usr/ports/devel/camp/work/camp-2025.09.0/extern/blt/thirdparty_builtin/googletest/googletest/src/gtest.cc:2696
#7  0x000000002beec8dc in testing::TestInfo::Run (this=0x2c8242a0)
    at /usr/ports/devel/camp/work/camp-2025.09.0/extern/blt/thirdparty_builtin/googletest/googletest/src/gtest.cc:2845

Location in /usr/include/c++/v1/string_view:

#0  std::__1::basic_string_view<char, std::__1::char_traits<char> >::remove_prefix[abi:se190107](unsigned long) (this=0x7fffffffd798, __n=18446744073709551615)
    at /usr/include/c++/v1/string_view:421
#1  0x000000000020f8dd in camp::experimental::insertArgsString<std::__1::tuple<int&>, 0ul>(std::__1::basic_ostream<char, std::__1::char_traits<char> >&, std::__1::basi
c_string_view<char, std::__1::char_traits<char> >, std::__1::tuple<int&>&&, std::__1::integer_sequence<unsigned long, 0ul>)::{lambda(auto:1&&)#1}::operator()<int&>(std
::__1::tuple<int&>&&) (this=0x7fffffffd780, arg=@0x7fffffffda8c: 7) at /usr/ports/devel/camp/work/camp-2025.09.0/include/camp/helpers.hpp:404
#2  0x000000000020c728 in camp::experimental::insertArgsString<std::__1::tuple<int&>, 0ul> (str=..., arg_names=..., args_tuple=...)
    at /usr/ports/devel/camp/work/camp-2025.09.0/include/camp/helpers.hpp:410
#3  0x000000000020a7fe in CampErrors_InsertArgsString_Test::TestBody (this=0x2c82d010) at /usr/ports/devel/camp/work/camp-2025.09.0/test/errors.cpp:143
#4  0x000000002bf34c54 in testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void> (object=0x2c82d010,
    method=&virtual testing::Test::TestBody(), location=0x2beabbed "the test body")
    at /usr/ports/devel/camp/work/camp-2025.09.0/extern/blt/thirdparty_builtin/googletest/googletest/src/gtest.cc:2621
#5  0x000000002bf0c434 in testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void> (object=0x2c82d010, method=&virtual testing::Test::TestBody(),
    location=0x2beabbed "the test body") at /usr/ports/devel/camp/work/camp-2025.09.0/extern/blt/thirdparty_builtin/googletest/googletest/src/gtest.cc:2657
#6  0x000000002beebe97 in testing::Test::Run (this=0x2c82d010)
    at /usr/ports/devel/camp/work/camp-2025.09.0/extern/blt/thirdparty_builtin/googletest/googletest/src/gtest.cc:2696
#7  0x000000002beec8dc in testing::TestInfo::Run (this=0x2c8242a0)
    at /usr/ports/devel/camp/work/camp-2025.09.0/extern/blt/thirdparty_builtin/googletest/googletest/src/gtest.cc:2845

Version: 2025.09.0
clang-19
FreeBSD 14.3

Start with include/camp/helpers.hpp around line 404, where the trace reports the failure, and inspect the calling test in test/errors.cpp around line 143. Run the affected tests and determine the corresponding second failure; done means both tests complete without the Illegal instruction error on the reported environment.