Avoid error deleting non-existent directory

src/hpc_multibench/test_bench.py

@@ -148,7 +148,7 @@ def record(self, args: Namespace) -> None:
         print(f"Recording data from test bench '{self.name}'")
 
         # Optionally clobber directory
-        if not args.no_clobber:
+        if not args.no_clobber and self.output_directory.exists():
             rmtree(self.output_directory)
 
         # Realise run configurations from list of instantiations