Segmentation Fault when processing yaml file

[Rwardc]

When processing this yaml file (which may be malformed), a segfault is encountered in verifier_server.cc:

meta:
  version: '1.0'


sessions:
  - protocol: [ { name: tcp }, {name: ip} ]
    transactions:
    - client-request:
        method: GET
        url: http://127.0.0.1
        version: '1.1'
        headers:
        fields:
          - [ Host, 127.0.0.1:8080 ]
          - [ Connection, Keep-Alive ]
          - [ uuid, the-transaction ]
        content:
          size: 0
      uuid: first-transaction

  
    proxy-response:
      content:
        encoding: plain
        size: 0
      headers:
        fields:
        - [ Connection, keep-alive ]
      reason: OK
      status: 200

Segfault output from gdb:

(gdb) run run --listen-http 127.0.0.1:8080 /c/Code/git/verifier-tests/simple.yaml
Starting program: /mnt/c/Code/git/proxy-verifier/bin/verifier-server run --listen-http 127.0.0.1:8080 /c/Code/git/verifier-tests/simple.yaml
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
ServerReplayFileHandler::txn_close (this=0x7ffffffebf00) at local/src/server/verifier-server.cc:547
547             _txn_node->Mark().line);

Expected Behavior:
Even when processing a bad yaml file, an informative error should be printed instead.

[Rwardc]

Back trace for the previous segfault:

#0  ServerReplayFileHandler::txn_close (this=0x7ffffffebf00) at local/src/server/verifier-server.cc:547
#1  0x000000000049023d in YamlParser::load_replay_file (path=..., handler=...) at local/src/core/YamlParser.cc:1406
#2  0x00000000004212b7 in operator() (file=..., __closure=<optimized out>) at local/src/server/verifier-server.cc:975
#3  0x00000000004213cd in std::__invoke_impl<swoc::_1_5_1::Errata, Engine::command_run()::<lambda(const swoc::_1_5_1::file::path&)>&, const swoc::_1_5_1::file::path&> (__f=...) at /usr/local/include/c++/11.3.0/bits/invoke.h:61
#4  std::__invoke_r<swoc::_1_5_1::Errata, Engine::command_run()::<lambda(const swoc::_1_5_1::file::path&)>&, const swoc::_1_5_1::file::path&> (__fn=...) at /usr/local/include/c++/11.3.0/bits/invoke.h:116
#5  std::_Function_handler<swoc::_1_5_1::Errata(const swoc::_1_5_1::file::path&), Engine::command_run()::<lambda(const swoc::_1_5_1::file::path&)> >::_M_invoke(const std::_Any_data &, const swoc::_1_5_1::file::path &) (__functor=...,
    __args#0=...) at /usr/local/include/c++/11.3.0/bits/std_function.h:291
#6  0x0000000000490f38 in std::function<swoc::_1_5_1::Errata (swoc::_1_5_1::file::path const&)>::operator()(swoc::_1_5_1::file::path const&) const (__args#0=..., this=0x7ffffffecdf0) at /usr/local/include/c++/11.3.0/bits/std_function.h:590
#7  YamlParser::load_replay_files(swoc::_1_5_1::file::path const&, std::function<swoc::_1_5_1::Errata (swoc::_1_5_1::file::path const&)>, int) (path=..., loader=..., n_threads=n_threads@entry=10) at local/src/core/YamlParser.cc:1435
#8  0x0000000000424099 in Engine::command_run (this=<optimized out>)
    at /usr/local/include/c++/11.3.0/ext/new_allocator.h:89
#9  0x0000000000415308 in main (argv=<optimized out>) at local/src/server/verifier-server.cc:1167

This is due to a missing server-response in the file. According to the json schema, server-response is not a required field.