[BUG] Merging via graph is broken

[liamtbrand]

Describe the bug
As discussed in #298 the merging functionality is currently broken. The code for this is found in graphSetup.ts.

The current code fails to execute the merging when the branches have been dragged together. See the code snippet below.

network.on('dragStart', function(callback) {
  startP = callback.pointer.canvas;
});

network.on('dragEnd', function(cb) {
  fromNode = cb.nodes[0];
  network.moveNode(fromNode, startP.x, startP.y);
  secP = cb.pointer.DOM;
}, false);

network.on('animationFinished', function() {
  if (fromNode !== null && secP !== null) {
    const toNode = network.getNodeAt(secP);

    if (fromNode !== toNode && (nodes.get(fromNode)['shape'] === 'box') && (nodes.get(toNode)['shape'] === 'box')) {
      mergeCommits(nodes.get(fromNode)['title']);
    }
  }
  fromNode = null;
  secP = null;
});

Changing this to the below code snippet results in correctly calling the merge function, however while the console states that the merge is happening, it doesn't happen, and the state of the repository remains the same.

network.on('dragStart', function(callback) {
  startP = callback.pointer.canvas;
});

network.on('dragEnd', function(cb) {
  fromNode = cb.nodes[0];
  network.moveNode(fromNode, startP.x, startP.y);
  secP = cb.pointer.DOM;

  if (fromNode !== null && secP !== null) {
    const toNode = network.getNodeAt(secP);
    console.log("attempting to merge")
    if (fromNode !== toNode && (nodes.get(fromNode)['shape'] === 'box') && (nodes.get(toNode)['shape'] === 'box')) {
      console.log("doing merge")
      mergeCommits(nodes.get(fromNode)['title']);
    }
  }

  fromNode = null;
  secP = null;

}, false);

To reproduce
Steps to reproduce the behavior:

1. Open VisualGit
2. Open a repository containing multiple branches
3. Drag branch labels together
4. Observe the lack of merging
5. Repeat steps 1 to 4 with the supplied code snippet replacement
6. Observe merge messages but no merge

Expected behavior / Acceptance criteria
Dragging a branch label onto the current branch label should successfully merge the branch into the current branch.

Screenshots
Currently using the provided code snippet the branch attempts to merge but this fails.
See the console output in the screenshot provided below.

Machine Specifications

Additional context
See issue #298 for more context.

Related issues
Fixing this bug will allow us to do issue #320.

[liamtbrand]

Also see: http://visjs.org/docs/network/

[rmberriman]

Approved!

[SamuelZheng11]

Approved

[twchen97]

Approved.