Fix crash when an invalid URI is parsed and error handling is attempted

[crr0004]

Summary

When you pass in a payload with an invalid URI in a build with assertions enabled, it will crash.
Consuming the error from the failed URI parse prevents the error.

The crash is caused by the llvm::expected having protection around trying to deconstruct without consuming the error first.

[kadircet]

thanks, lgtm! please provide an email for attribution if i should land this for you.

[crr0004]

In D99872#2670310, @kadircet wrote:

thanks, lgtm! please provide an email for attribution if i should land this for you.

Great! I wasn't sure if I should create a unit test for it. I couldn't see a place where Protocol was being tested.

My email is [e-mail]

clang-tools-extra/clangd/Protocol.cpp

if (!Resolved)
     return Resolved.takeError();
   return URIForFile(std::move(*Resolved));
 }
 
 bool fromJSON(const llvm::json::Value &E, URIForFile &R, llvm::json::Path P) {
   if (auto S = E.getAsString()) {
     auto Parsed = URI::parse(*S);
     if (!Parsed) {
+      consumeError(Parsed.takeError());
       P.report("failed to parse URI");
       return false;
     }
     if (Parsed->scheme() != "file" && Parsed->scheme() != "test") {
       P.report("clangd only supports 'file' URI scheme for workspace files");
       return false;
     }
     // "file" and "test" schemes do not require hint path.