[clangd] Fix mac buildbot failure.

[hokein]

Summary

Fix a use-after-free bug. The inner loop may add element to Dependencies
vector, which may cause memory reallocation of the vector.

Also fix an assertion, we have to take errors when llvm::Expected holds an
error.

[hokein]

remove unrelated blank changes.

[kadircet]

https://reviews.llvm.org/D56656 has landed to fix that issue

[hokein]

In D56655#1356000, @kadircet wrote:

https://reviews.llvm.org/D56656 has landed to fix that issue

Thanks! I have verified that the test failure is gone after your patch.

clangd/index/Background.cpp

BackgroundIndex::loadShard(const tooling::CompileCommand &Cmd,
   std::string AbsolutePath = getAbsolutePath(Cmd).str();
   // Up until we load the shard related to a dependency it needs to be
   // re-indexed.
   Dependencies.emplace_back(AbsolutePath, true);
   InQueue.insert(AbsolutePath);
   // Goes over each dependency.
   for (size_t CurrentDependency = 0; CurrentDependency < Dependencies.size();
        CurrentDependency++) {
-    llvm::StringRef CurDependencyPath = Dependencies[CurrentDependency].Path;
+    std::string CurDependencyPath = Dependencies[CurrentDependency].Path;
     // If we have already seen this shard before(either loaded or failed) don't
     // re-try again. Since the information in the shard won't change from one TU
     // to another.
     if (!LoadedShards.try_emplace(CurDependencyPath).second) {
       // If the dependency needs to be re-indexed, first occurence would already
       // have detected that, so we don't need to issue it again.
       Dependencies[CurrentDependency].NeedsReIndexing = false;
       continue;
     }
 
     auto Shard = IndexStorage->loadShard(CurDependencyPath);
     if (!Shard || !Shard->Sources) {
       // File will be returned as requiring re-indexing to caller.
       vlog("Failed to load shard: {0}", CurDependencyPath);
       continue;
     }
     // These are the edges in the include graph for current dependency.
     for (const auto &I : *Shard->Sources) {
       auto U = URI::parse(I.getKey());
-      if (!U)
+      if (!U) {
+        elog("Failed to parse URI {0}: {1}", I.getKey(), U.takeError());
         continue;
+      }
       auto AbsolutePath = URI::resolve(*U, CurDependencyPath);
-      if (!AbsolutePath)
+      if (!AbsolutePath) {
+        elog("Failed to resolve URI {0}: {1}", I.getKey(),
+             AbsolutePath.takeError());
         continue;
+      }
       // Add file as dependency if haven't seen before.
       if (InQueue.try_emplace(*AbsolutePath).second)
         Dependencies.emplace_back(*AbsolutePath, true);
       // The node contains symbol information only for current file, the rest is
       // just edges.
       if (*AbsolutePath != CurDependencyPath)
         continue;