From 17dd24a7088679f8f2cb96dd41d12b377693a008 Mon Sep 17 00:00:00 2001
From: Anthony Fu <anthonyfu117@hotmail.com>
Date: Thu, 16 Sep 2021 08:56:25 +0800
Subject: [PATCH] fix: cleanup sources in transform map

close https://github.com/antfu/unplugin-vue-components/issues/138
---
 src/webpack/loaders/transform.ts | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/webpack/loaders/transform.ts b/src/webpack/loaders/transform.ts
index 57e9203..9116e43 100644
--- a/src/webpack/loaders/transform.ts
+++ b/src/webpack/loaders/transform.ts
@@ -19,7 +19,23 @@ export default async function transform (this: LoaderContext<any>, source: strin
   if (res == null) {
     callback(null, source, map)
   } else if (typeof res !== 'string') {
-    callback(null, res.code, map == null ? map : (res.map || map))
+    // only pass sourcemap when sourcemap is provided upstream
+    const newMap = map == null ? map : (res.map || map)
+    // clean up nullish sources produced by magic-string
+    if (newMap && Array.isArray(newMap.sources)) {
+      const excluded: number[] = []
+      newMap.sources = newMap.sources.filter((i:any, idx:number) => {
+        if (i == null) {
+          excluded.push(idx)
+          return false
+        }
+        return true
+      })
+      newMap.sources = newMap.sources.filter((_: any, idx: number) => {
+        return !excluded.includes(idx)
+      })
+    }
+    callback(null, res.code, newMap)
   } else {
     callback(null, res, map)
   }