Graph2D breaks when zooming in/out

[mojoaxel]

You can reproduce the problem using "examples/graph2d/08_performance.html":

This was introduced after 4.17.0 and needs to be fixed before the 4.18 release!!

[mojoaxel]

Also the console shows errors:

Invalid type received for "sampling". Expected: bool. Received [boolean] "true"
Problem value found at: 
options = {
  sampling
}

Invalid type received for "enabled". Expected: bool. Received [boolean] "false"
Problem value found at: 
options = {
  drawPoints: {
    enabled
  }
}

Invalid type received for "interpolation". Expected: object, bool. Received [boolean] "false"
Problem value found at: 
options = {
  interpolation
}

Errors have been found in the supplied options object.

[mojoaxel]

There were two issues here. One is the problem described in #2500. The other one is a really strange:

GraphGroup.js:41 Uncaught TypeError: Cannot read property 'x' of undefined

This is caused by because in LineGraph.js#L481 the comparison between the IDs ("0" !== 0) fails. We have to make sure that internal ids are always of the same type.