Expand ~ to user directory in path-like variables

run-exp.py

@@ -40,7 +40,7 @@ class Variable:
         assert var_type in ["file", "range"], "Unsupported variable type."
 
         if var_type == "file":
-            directory = pathlib.Path(value_config["directory"])
+            directory = pathlib.Path(value_config["directory"]).expanduser()
             assert directory.exists() and directory.is_dir()
 
             values = list(directory.iterdir())