Can't run run_slam node with SocketViewer (with Pangolin everything is OK)

[andyreynolds99]

Describe the bug

Can't run run_slam node with SocketViewer (with Pangolin everything is OK).

To Reproduce

Steps to reproduce the behavior:

1. run the node rosrun stella_vslam_ros run_slam -v ../orb_vocab.fbow -c ../stella_vslam/example/euroc/EuRoC_mono.yaml --viewer socket_publisher
2. Setup image topic: rosrun image_transport republish raw in:=/camera/infra1/image_rect_raw raw out:=/camera/image_raw
3. run the rosbag file: rosbag play MH_01_easy.bag
4. See error:

   
   socket_publisher not linked

Allowed options: (some stuff)

free(): invalid pointer Segmentation fault (core dumped)

The same error and output is when running `./run_euroc_slam`. Maybe it's simpler to fix it in the examples due to easier debugging.

config file:

```yaml
# EuRoC monocular model

Camera:
  name: "EuRoC monocular"
  setup: "monocular"
  model: "perspective"

  fx: 458.654
  fy: 457.296
  cx: 367.215
  cy: 248.375

  k1: -0.28340811
  k2: 0.07395907
  p1: 0.00019359
  p2: 1.76187114e-05
  k3: 0.0

  fps: 20.0
  cols: 752
  rows: 480

  color_order: "Gray"

Preprocessing:
  min_size: 800

Feature:
  name: "default ORB feature extraction setting"
  scale_factor: 1.2
  num_levels: 8
  ini_fast_threshold: 20
  min_fast_threshold: 7

Mapping:
  backend: "g2o"
  baseline_dist_thr_ratio: 0.02
  redundant_obs_ratio_thr: 0.9
  num_covisibilities_for_landmark_generation: 20
  num_covisibilities_for_landmark_fusion: 20
  erase_temporal_keyframes: false
  num_temporal_keyframes: 15

Tracking:
  backend: "g2o"
  enable_temporal_keyframe_only_tracking: false

KeyframeInserter:
  wait_for_local_bundle_adjustment: false

Relocalizer:
  search_neighbor: true

LoopDetector:
  backend: "g2o"

System:
  map_format: "msgpack"
  num_grid_cols: 47
  num_grid_rows: 30

PangolinViewer:
  keyframe_size: 0.07
  keyframe_line_width: 1
  graph_line_width: 1
  point_size: 2
  camera_size: 0.08
  camera_line_width: 3
  viewpoint_x: 0
  viewpoint_y: -0.65
  viewpoint_z: -1.9
  viewpoint_f: 400

Expected behavior

I expected when opening in browser https://127.0.0.1:3001 something like Pangolin shows will be seen, but there is and empty environment (web server is up and running).

Screenshots or videos

Environment

• Hardware: [e.g. PC x86_64]
• CPU: [e.g. Ryzen 5800u]
• OS: [e.g. Ubuntu 20.04]
• Commit id: [e.g. stella_vslam=577cb04d9245aa68b0905212293a802292d01787, stella_vslam_ros=fdbd287d80a3a5cc4ac1a143dc937adb4697b120]
• Install procedure: [docker or native]
• dataset: [e.g. EuRoC MH_01_easy]