Updated error message in space.c to reflect the change from h_max to a number of top-level cells.

src/space.c

@@ -243,7 +243,8 @@ void space_regrid(struct space *s, int verbose) {
         "is switched on.\nThis error is often caused by any of the "
         "followings:\n"
         " - too few particles to generate a sensible grid,\n"
-        " - the initial value of 'SPH:max_smoothing_length' is too large,\n"
+        " - the initial value of 'Scheduler:max_top_level_cells' is too "
+        "small,\n"
         " - the (minimal) time-step is too large leading to particles with "
         "predicted smoothing lengths too large for the box size,\n"
         " - particle with velocities so large that they move by more than two "