Add checking if the build directory exists and move expression after docstring

tools/idf_py_actions/serial_ext.py

@@ -109,10 +109,10 @@ def action_extensions(base_actions, project_path):
         run_tool("idf_monitor", monitor_args, args.project_dir)
 
     def flash(action, ctx, args):
-        ensure_build_directory(args, ctx.info_name)
         """
         Run esptool to flash the entire project, from an argfile generated by the build system
         """
+        ensure_build_directory(args, ctx.info_name)
         if args.port is None:
             args.port = _get_default_serial_port()
 
@@ -120,6 +120,7 @@ def action_extensions(base_actions, project_path):
                                   "ESPBAUD": str(args.baud)})
 
     def erase_flash(action, ctx, args):
+        ensure_build_directory(args, ctx.info_name)
         esptool_args = _get_esptool_args(args)
         esptool_args += ["erase_flash"]
         run_tool("esptool.py", esptool_args, args.build_dir)