fix: generate sourcemaps even if previous maps are provided

Author: znck

src/style-compiler/index.js

@@ -21,10 +21,6 @@ module.exports = function compileStyle (style, filename, config) {
 
   // source map
   if (config.needMap) {
-    if (!style.map) {
-      throw Error('Previous source map is missing.')
-    }
-
     options.map = {
       inline: false,
       annotation: false,

test/style-compiler.test.js

@@ -10,3 +10,14 @@ test('should rewrite scoped style', () => {
   const compiled = compiler(style, 'foo.vue', { scopeId: 'xxx', needMap: false })
   expect(compiled.code.indexOf('.foo[xxx]')).toBeGreaterThan(-1)
 })
+
+test('should generate sourcemap', () => {
+  const style = {
+    code: '.foo { color: red }',
+    descriptor: {
+      scoped: true
+    }
+  }
+  const compiled = compiler(style, 'foo.vue', { scopeId: 'xxx' })
+  expect(compiled.map).toBeTruthy()
+})