Add runtime checks

src/style-spec/expression/index.js

@@ -78,7 +78,8 @@ export class StyleExpression {
 
         try {
             const val = this.expression.evaluate(this._evaluator);
-            if (val === null || val === undefined) {
+            // eslint-disable-next-line no-self-compare
+            if (val === null || val === undefined || (typeof val === 'number' && val !== val)) {
                 return this._defaultValue;
             }
             if (this._enumValues && !(val in this._enumValues)) {

test/unit/style-spec/fixture/numbers.output-api-supported.json

@@ -0,0 +1,25 @@
+[
+    {
+      "line": 42,
+      "message": "layers[2].paint.circle-radius: -1 is less than the minimum value 0"
+    },
+    {
+      "message": "layers[3].paint.circle-radius: number expected, null found"
+    },
+    {
+      "line": 58,
+      "message": "layers[4].paint.circle-radius: missing required property \"stops\""
+    },
+    {
+      "line": 66,
+      "message": "layers[5].paint.circle-radius: number expected, array found"
+    },
+    {
+      "line": 74,
+      "message": "layers[6].paint.circle-radius: number expected, boolean found"
+    },
+    {
+      "line": 6,
+      "message": "source.data: Unsupported property \"data\""
+    }
+  ]