fix: skip empty benchmarks to avoid infinite loops when CODSPEED_MODE=off

When `CODSPEED_MODE=off`, empty benchmark bodies (which don't run the
`KeepRunning()` loop) fail to advance iteration counts. Instead of
triggering a hard `BM_CHECK` failure or stalling in an infinite loop,
the runner now intercepts the state and gracefully drops a meaningful
error message.

References:
- Issue: google/benchmark#1962
- Pull Request: google/benchmark#1976

Author: OsamaAhmad00

google_benchmark/src/benchmark_runner.cc

@@ -143,8 +143,11 @@ void RunInThread(const BenchmarkInstance* b, IterationCount iters,
 
   State st = b->__codspeed_root_frame__Run(iters, thread_id, &timer, manager,
                     perf_counters_measurement, profiler_manager_, is_warmup);
-  BM_CHECK(st.skipped() || st.iterations() >= st.max_iterations)
-      << "Benchmark returned before State::KeepRunning() returned false!";
+  if (!(st.skipped() || st.iterations() >= st.max_iterations)) {
+    st.SkipWithError(
+        "The benchmark didn't run, nor was it explicitly skipped. Please call "
+        "'SkipWithXXX` in your benchmark as appropriate.");
+  }
   {
     MutexLock l(manager->GetBenchmarkMutex());
     internal::ThreadManager::Result& results = manager->results;

google_benchmark/test/skip_with_error_test.cc

@@ -181,6 +181,15 @@ ADD_CASES("BM_error_while_paused", {{"/1/threads:1", true, "error message"},
                                     {"/2/threads:4", false, ""},
                                     {"/2/threads:8", false, ""}});
 
+void BM_malformed(benchmark::State&) {
+  // NOTE: empty body wanted. No thing else.
+}
+BENCHMARK(BM_malformed);
+ADD_CASES("BM_malformed",
+          {{"", true,
+            "The benchmark didn't run, nor was it explicitly skipped. Please "
+            "call 'SkipWithXXX` in your benchmark as appropriate."}});
+
 int main(int argc, char* argv[]) {
   benchmark::Initialize(&argc, argv);