Vega-Lite 3.4.0 compile function causes Uncaught RangeError: Maximum call stack size exceeded

I am using Vega and Vega-Lite inside of React and manually compiling Vega-Lite specs down to Vega. The following spec causes Uncaught RangeError: Maximum call stack size exceeded when manually passed into the compile() function. According to the stack trace it looks like something wonky is happening inside of the concat module. I was able to manually pass this same spec (with the $schema field changed) into Vega-Lite 2’s compile() function without a problem.

{
  "$schema":"https://vega.github.io/schema/vega-lite/v3.json",
  "width":630,
  "height":290,
  
  "autosize":{
    "type":"fit",
    "contains":"padding"
  },
  "config":{
    "axis":{
      "labelColor":"#888c95",
      "titleColor":"#888c95",
      "domain":false
    },
    "legend":{
      "labelColor":"#888c95",
      "titleColor":"#888c95"
    },
    "scale":{
      "bandPaddingInner":0,
      "round":false
    },
    "view":{
      "fill":"#414855",
      "stroke":"transparent"
    }
  },
  "data":{
    ...
  },
  "mark":"rect",
  "encoding":{
    "y":{
      "field":"time",
      "type":"ordinal",
      "timeUnit":"day",
      "sort":[
        "mon",
        "tue",
        "wed",
        "thu",
        "fri",
        "sat",
        "sun"
      ]
    },
    "x":{
      "field":"time",
      "type":"ordinal",
      "timeUnit":"hours"
    },
    "size":{
      "field":"value",
      "type":"quantitative",
      "aggregate":"mean"
    },
    "color":{
      "field":"value",
      "aggregate":"mean",
      "type":"quantitative",
      "scale":{
        "scheme":"viridis"
      }
    }
  }
}

[domoritz]

Thanks for the context. If we have an infinite loop, I’d want to fix that. Can you keep looking for an example that creates this issue in the editor? I can look into and fix it then.

[cassandraoconnell]

Okay @domoritz, we figured out what’s going on here. The error was happening because we use Babel to transpile our code, and this line of code was somehow being generated as having a recursive reference to this. Interestingly enough, changing the spread operator in that line to Array.from(this) fixed our problem.

We’re going to tell Babel to ignore all of our Vega imports for now, as we’re having some more issues with mixing Babel and Vega/Vega-Lite (which we’re still figuring out). It all seems to revolve around overriding the Set prototype though—once that’s figured out, I’ll open a new issue if it is indeed a Vega problem.