[torque-ls] Fix crash when looking up definitions

This CL fixes a crash that happens on a goto definition lookup for a
file with no data attached to it.

Drive-by: Collect language server data even on compilation failures.

R=tebbi@chromium.org

Bug: v8:8880
Change-Id: Ia6323204391da3e64058e1fe47f87162186c15cd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1583721Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61012}

src/torque/server-data.cc

@@ -17,7 +17,12 @@ void LanguageServerData::AddDefinition(SourcePosition token,
 
 base::Optional<SourcePosition> LanguageServerData::FindDefinition(
     SourceId source, LineAndColumn pos) {
-  for (const DefinitionMapping& mapping : Get().definitions_map_.at(source)) {
+  if (!source.IsValid()) return base::nullopt;
+
+  auto iter = Get().definitions_map_.find(source);
+  if (iter == Get().definitions_map_.end()) return base::nullopt;
+
+  for (const DefinitionMapping& mapping : iter->second) {
     SourcePosition current = mapping.first;
     if (current.Contains(pos)) return mapping.second;
   }

src/torque/torque-compiler.cc

@@ -94,8 +94,7 @@ TorqueCompilerResult CollectResultFromContextuals() {
 }
 
 TorqueCompilerResult ResultFromError(TorqueError& error) {
-  TorqueCompilerResult result;
-  result.source_file_map = SourceFileMap::Get();
+  TorqueCompilerResult result = CollectResultFromContextuals();
   result.error = error;
   return result;
 }

test/unittests/torque/ls-server-data-unittest.cc

@@ -70,6 +70,15 @@ TEST(LanguageServer, GotoTypeDefinitionExtends) {
   EXPECT_EQ(*maybe_position, (SourcePosition{id, {2, 5}, {2, 7}}));
 }
 
+TEST(LanguageServer, GotoTypeDefinitionNoDataForFile) {
+  LanguageServerData::Scope server_data_scope;
+  SourceFileMap::Scope file_scope;
+  SourceId test_id = SourceFileMap::AddSource("test.tq");
+
+  // Regression test, this step should not crash.
+  EXPECT_FALSE(LanguageServerData::FindDefinition(test_id, {0, 0}));
+}
+
 }  // namespace torque
 }  // namespace internal
 }  // namespace v8