Fix format expression options validation

src/style-spec/util/unbundle_jsonlint.js

@@ -1,7 +1,10 @@
+function isPrimitive(value) {
+    return value instanceof Number || value instanceof String || value instanceof Boolean;
+}
 
 // Turn jsonlint-lines-primitives objects into primitive objects
 export function unbundle(value) {
-    if (value instanceof Number || value instanceof String || value instanceof Boolean) {
+    if (isPrimitive(value)) {
         return value.valueOf();
     } else {
         return value;
@@ -11,7 +14,14 @@ export function unbundle(value) {
 export function deepUnbundle(value) {
     if (Array.isArray(value)) {
         return value.map(deepUnbundle);
+    } else if (value instanceof Object && !isPrimitive(value)) {
+        const unbundledValue = {};
+        for (const key in value) {
+            unbundledValue[key] = deepUnbundle(value[key]);
+        }
+        return unbundledValue;
     }
+
     return unbundle(value);
 }
 

test/unit/style-spec/fixture/text-field-format.input.json

@@ -0,0 +1,45 @@
+{
+  "version": 8,
+  "sources": {
+    "point": {
+      "type": "geojson",
+      "data": {
+        "type": "FeatureCollection",
+        "features": [
+          {
+            "type": "Feature",
+            "properties": {
+              "name": "Napoli",
+              "name_en": "Naples",
+              "name_color": "blue"
+            },
+            "geometry": {
+              "type": "Point",
+              "coordinates": [ 0, 0 ]
+            }
+          }
+        ]
+      }
+    }
+  },
+  "glyphs": "local://glyphs/{fontstack}/{range}.pbf",
+  "layers": [
+    {
+      "id": "text",
+      "type": "symbol",
+      "source": "point",
+      "layout": {
+        "text-field": [
+          "format",
+          "x",
+          { "font-scale": 1.5 }
+        ],
+        "text-font": [
+          "Open Sans Semibold",
+          "Arial Unicode MS Bold"
+        ],
+        "text-size": 20
+      }
+    }
+  ]
+}

test/unit/style-spec/fixture/text-field-format.output.json

@@ -0,0 +1 @@
+[]

yarn.lock

@@ -7,7 +7,7 @@
   resolved "https://registry.yarnpkg.com/@babel/code-frame/-/code-frame-7.0.0.tgz#06e2ab19bdb535385559aabb5ba59729482800f8"
   integrity sha512-OfC2uemaknXr87bdLUkWog7nYuliM9Ij5HUcajsVcMCpQrcLmtxRbVFTIqmcSkSeYRBFBRxs2FiUqFJDLdiebA==
   dependencies:
-    "@babel/highlight" "^7.0.0"
+    "@babel/highlight" "~7.0.0"
 
 "@babel/core@>=7.1.0", "@babel/core@^7.1.2":
   version "7.4.3"