clang-tidy error: Null pointer passed as an argument to strlen

```
/home/runner/work/binlog/binlog/test/integration/IntegrationTest.cpp:168:13: note: Calling constructor for 'child'
bp::child bread(g_bread_path, "-f", "%m", bp::std_in < binary, bp::std_out > text);
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/child.hpp:35:13: note: Calling 'execute_impl'
: child(::boost::process::detail::execute_impl(std::forward(args)...)) {}
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/execute_impl.hpp:275:12: note: Calling 'basic_execute_impl'
return basic_execute_impl(
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/execute_impl.hpp:267:12: note: Calling 'executor::operator()'
return exec();
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:308:16: note: Calling 'executor::invoke'
return invoke(has_ignore_error(), shall_use_vfork());
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:380:13: note: Assuming the condition is false
if (::pipe(p.p) == -1)
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:380:9: note: Taking false branch
if (::pipe(p.p) == -1)
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:385:13: note: Assuming the condition is false
if (::fcntl(p.p[1], F_SETFD, FD_CLOEXEC) == -1)
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:385:9: note: Taking false branch
if (::fcntl(p.p[1], F_SETFD, FD_CLOEXEC) == -1)
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:394:9: note: Taking false branch
if (_ec)
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:400:13: note: Assuming the condition is true
if (cmd_style)
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:400:9: note: Taking true branch
if (cmd_style)
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:401:13: note: Calling 'executor::prepare_cmd_style'
prepare_cmd_style();
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:274:13: note: Left side of '&&' is true
if ((prepare_cmd_style_fn.find('/') == std::string::npos) && ::access(prepare_cmd_style_fn.c_str(), X_OK))
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:274:70: note: Assuming the condition is true
if ((prepare_cmd_style_fn.find('/') == std::string::npos) && ::access(prepare_cmd_style_fn.c_str(), X_OK))
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:274:9: note: Taking true branch
if ((prepare_cmd_style_fn.find('/') == std::string::npos) && ::access(prepare_cmd_style_fn.c_str(), X_OK))
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:277:21: note: Assuming pointer value is null
while ((*e != nullptr) && !boost::starts_with(*e, "PATH="))
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:277:21: note: Assuming the condition is false
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:277:36: note: Left side of '&&' is false
while ((*e != nullptr) && !boost::starts_with(*e, "PATH="))
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:280:13: note: Taking true branch
if (e != nullptr)
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/process/detail/posix/executor.hpp:283:17: note: Calling 'split'
boost::split(path, *e, boost::is_any_of(":"));
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/algorithm/string/split.hpp:158:20: note: Calling 'iter_split'
return ::boost::algorithm::iter_split(
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/algorithm/string/iter_find.hpp:161:110: note: Passing value via 1st parameter 'r'
iterator_range::type> lit_input(::boost::as_literal(Input));
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/algorithm/string/iter_find.hpp:161:90: note: Calling 'as_literal'
iterator_range::type> lit_input(::boost::as_literal(Input));
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/range/as_literal.hpp:145:42: note: Passing null pointer value via 1st parameter 'r'
return range_detail::make_range( r, range_detail::is_char_ptr(r) );
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/range/as_literal.hpp:145:16: note: Calling 'make_range'
return range_detail::make_range( r, range_detail::is_char_ptr(r) );
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/range/as_literal.hpp:129:54: note: Passing null pointer value via 1st parameter 's'
return iterator_range( r, r + length(r) );
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/range/as_literal.hpp:129:47: note: Calling 'length'
return iterator_range( r, r + length(r) );
^
/opt/hostedtoolcache/boost/1.72.0/x64/include/boost/range/as_literal.hpp:43:20: note: Null pointer passed as an argument to a 'nonnull' parameter
return strlen( s );
```

https://github.com/Morgan-Stanley/binlog/pull/96/checks?check_run_id=1390629482