't_range' should be a float, obviously.

marlpde/parameters.py

@@ -205,7 +205,7 @@ class Solver():
     '''
     dt: float = 1.e-6
     # t_range is the integration time in units of T*.
-    t_range: int = 1
+    t_range: float = 1
     solver: str = "scipy"
     # Beware that "scheme" and "adaptive" will only be propagated if you have 
     # chosen py-pde's native "explicit" solver above.