Format axis with custom currency marks

[the21st]

I am attempting to format my Y axis with an € (EUR) symbol like this:

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "description": "A simple bar chart with embedded data.",
  "data": {
    "values": [
      {"a": "A", "b": 28}, {"a": "B", "b": 55}, {"a": "C", "b": 43},
      {"a": "D", "b": 91}, {"a": "E", "b": 81}, {"a": "F", "b": 53},
      {"a": "G", "b": 19}, {"a": "H", "b": 87}, {"a": "I", "b": 52}
    ]
  },
  "mark": "bar",
  "encoding": {
    "x": {"field": "a", "type": "nominal"},
    "y": {"field": "b", "type": "quantitative", "axis": {"format": "€.2f"}}
  }
}

Open the Chart in the Vega Editor

However, this is producing errors and no chart:

Is there a way to customize the currency symbol in the spec?