Ill-formed JSON produced by Altair (NaN at line 111)

spec.json

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            "\u2264 14 d\u00edas",
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          "title": "Rengl\u00f3n (d\u00edas)"
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          "field": "tier_order"
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            "title": "Resultados en rengl\u00f3n (crudo)"
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            "title": "Total (crudo)"
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          {
            "type": "quantitative",
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            "format": ".1f",
            "title": "Resultados en rengl\u00f3n (promedio 7)"
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          {
            "type": "quantitative",
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            "format": ".1f",
            "title": "Total (promedio 7)"
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            "format": ".1%",
            "title": "% de total (promedio 7)"
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            "ticks": false
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          "field": "bulletin_date",
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          "field": "mean_count",
          "scale": {
            "domain": [
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          },
          "title": "Resultados moleculares (promedio 7 d\u00edas)"
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          "title": "Fecha de bolet\u00edn"
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            "labelExpr": "if(datum.value < 1.0, datum.label, '')"
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