fix(counter-style): additive systems with only one symbol mapped to 0

Such systems should have range [0, 0].

Author: jsamr

packages/counter-style/src/CounterStyle.ts

@@ -122,8 +122,8 @@ const CounterStyle: Readonly<CounterStyleStatic> = Object.freeze({
       }
     });
     return style.withRange(
-      values.length ? values[values.length - 1] : 0,
-      values.length ? Infinity : -1
+      0 in symbols ? 0 : Math.max(values.length - 1, 0),
+      values.length ? Infinity : 0 in symbols ? 0 : -1
     );
   }
 });

packages/counter-style/src/__tests__/CounterStyle.test.ts

@@ -106,6 +106,10 @@ describe('CounterStyle', () => {
         (CounterStyle.additive({}) as CounterStyleRendererInt).engine.specs
           .range
       ).toMatchObject({ min: 0, max: -1 });
+      expect(
+        (CounterStyle.additive({ 0: '0' }) as CounterStyleRendererInt).engine
+          .specs.range
+      ).toMatchObject({ min: 0, max: 0 });
       expect(
         (CounterStyle.additive({ 1: '0', 2: '1' }) as CounterStyleRendererInt)
           .engine.specs.range