fix: fix the error when values are all null in linear scale.

src/chart/controller/scale.js

@@ -9,6 +9,12 @@ const SCALE_TYPES_MAP = {
 };
 
 function getRange(values) {
+  if (!values.length) { // 空数组需要手动设置 min:0 max:0，否则 linear scale 会报错
+    return {
+      min: 0,
+      max: 0
+    };
+  }
   const max = Math.max.apply(null, values);
   const min = Math.min.apply(null, values);
   return {

test/bug/issue-140-spec.js

@@ -0,0 +1,44 @@
+const expect = require('chai').expect;
+const F2 = require('../../src/core');
+require('../../src/geom/line');
+
+const canvas = document.createElement('canvas');
+canvas.width = 500;
+canvas.height = 500;
+canvas.id = 'issue-140';
+canvas.style.position = 'fixed';
+canvas.style.top = 0;
+canvas.style.left = 0;
+document.body.appendChild(canvas);
+
+describe('issue 140', () => {
+  it('Linear scale values are all null.', function() {
+    const data = [
+      { type: '湿度/%', value: null, date: '2018-06-01 11:09:00' },
+      { type: '温度/℃', value: null, date: '2018-06-01 11:09:00' },
+      { type: '湿度/%', value: null, date: '2018-06-01 11:10:00' },
+      { type: '温度/℃', value: null, date: '2018-06-01 11:10:00' }
+    ];
+    const chart = new F2.Chart({
+      id: 'issue-140',
+      pixelRatio: window.devicePixelRatio
+    });
+    chart.source(data, {
+      value: {
+        nice: false
+      }
+    });
+    const line = chart.line().position('date*value').color('type');
+    chart.render();
+
+    const valueScale = line.getYScale();
+    expect(valueScale.min).to.equal(0);
+    expect(valueScale.max).to.equal(0);
+
+    chart.scale('value', null);
+    chart.changeData(data);
+    const newValueScale = line.getYScale();
+    expect(newValueScale.type).eql('identity');
+  });
+});
+