[clang-check][syntax]Crash in TreeBuilder::getDeclarationRange: dyn_cast<TagDecl> Assertion `detail::isPresent(Val) && "dyn_cast on a non-existent value"'` failed.

This input is generated by a fuzzer.
```cxx
template
concept X = x;
```

```
clang-check --tokens-dump example.cpp -- -xc++ -std=c++23
```

stacktrace
```
clang-check: /home/ubuntu2404/llvm-project-196067/llvm/include/llvm/Support/Casting.h:656: decltype(auto) llvm::dyn_cast(From*) [with To = clang::TagDecl; From = clang::Decl]: Assertion `detail::isPresent(Val) && "dyn_cast on a non-existent value"' failed.
#0 0x00005a384ee801f1 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x96d1f1)
#1 0x00005a384ee7cdac llvm::sys::RunSignalHandlers() (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x969dac)
#2 0x00005a384ee7cf0c SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
#3 0x00007a955ac45330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
#4 0x00007a955ac9eb2c __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
#5 0x00007a955ac9eb2c __pthread_kill_internal ./nptl/pthread_kill.c:78:10
#6 0x00007a955ac9eb2c pthread_kill ./nptl/pthread_kill.c:89:10
#7 0x00007a955ac4527e raise ./signal/../sysdeps/posix/raise.c:27:6
#8 0x00007a955ac288ff abort ./stdlib/abort.c:81:7
#9 0x00007a955ac2881b _nl_load_domain ./intl/loadmsgcat.c:1177:9
#10 0x00007a955ac3b517 (/lib/x86_64-linux-gnu/libc.so.6+0x3b517)
#11 0x00005a384f215181 clang::syntax::TreeBuilder::getDeclarationRange(clang::Decl*) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xd02181)
#12 0x00005a384f21c0a0 (anonymous namespace)::BuildTreeVisitor::WalkUpFromTemplateDecl(clang::TemplateDecl*) BuildTree.cpp:0:0
#13 0x00005a384f21faea clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::TraverseDeclContextHelper(clang::DeclContext*) BuildTree.cpp:0:0
#14 0x00005a384f23883b clang::RecursiveASTVisitor<(anonymous namespace)::BuildTreeVisitor>::TraverseTranslationUnitDecl(clang::TranslationUnitDecl*) BuildTree.cpp:0:0
#15 0x00005a384f21f439 clang::syntax::buildSyntaxTree(clang::syntax::Arena&, clang::syntax::TokenBufferTokenManager&, clang::ASTContext&) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xd0c439)
#16 0x00005a384e9134af (anonymous namespace)::DumpSyntaxTree::CreateASTConsumer(clang::CompilerInstance&, llvm::StringRef)::Consumer::HandleTranslationUnit(clang::ASTContext&) ClangCheck.cpp:0:0
#17 0x00005a3850749f9c clang::ParseAST(clang::Sema&, bool, bool) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x2236f9c)
#18 0x00005a384eed7271 clang::FrontendAction::Execute() (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x9c4271)
#19 0x00005a384ef23308 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xa10308)
#20 0x00005a384f1ffcb7 clang::tooling::FrontendActionFactory::runInvocation(std::shared_ptr, clang::FileManager*, std::shared_ptr, clang::DiagnosticConsumer*) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xceccb7)
#21 0x00005a384f1f9b2a clang::tooling::ToolInvocation::runInvocation(char const*, clang::driver::Compilation*, std::shared_ptr, std::shared_ptr) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xce6b2a)
#22 0x00005a384f1fc1e2 clang::tooling::ToolInvocation::run() (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xce91e2)
#23 0x00005a384f1fde19 clang::tooling::ClangTool::run(clang::tooling::ToolAction*) (/home/ubuntu2404/build-196067-assert/bin/clang-check+0xceae19)
#24 0x00005a384e898405 main (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x385405)
#25 0x00007a955ac2a1ca __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:74:3
#26 0x00007a955ac2a28b call_init ./csu/../csu/libc-start.c:128:20
#27 0x00007a955ac2a28b __libc_start_main ./csu/../csu/libc-start.c:347:5
#28 0x00005a384e912045 _start (/home/ubuntu2404/build-196067-assert/bin/clang-check+0x3ff045)
Aborted (core dumped)
```

Start with clang-tools-extra/clang-check and the syntax tree code in BuildTree.cpp, focusing on TreeBuilder::getDeclarationRange as shown in the stack trace. Run clang-check --tokens-dump on the provided example.cpp with -xc++ -std=c++23, then confirm the fuzzer input no longer triggers the assertion or aborts.

Written by the indexing model from the issue text.