fix error on module

hysop/tools/io_utils.py

@@ -312,12 +312,17 @@ class IOParams(namedtuple("IOParams", ['filename', 'filepath',
 
         dump_times_fp64 = tuple(map(np.float64, dump_times))
         dump_times_fp32 = tuple(map(np.float32, dump_times))
-
-        ram_path = IO.ram_path()
+        
         if force_ram_fs:
             enable_ram_fs = True
-            if (ram_path is None):
-                raise RuntimeError('Could not find any memory based filesystem (ramfs, tmpfs).')
+        
+        try:
+            ram_path = IO.ram_path()
+        except RuntimeError:
+            if force_ram_fs:
+                raise
+            else:
+                ram_path = None
 
         disk_filepath = None
         if enable_ram_fs and (ram_path is not None):