In the task_overlap function, escape early if the union is 0

examples/IsolatedGalaxy/IsolatedGalaxy_starformation/isolated_galaxy.yml

@@ -35,7 +35,7 @@ Statistics:
 
 # Parameters related to the initial conditions
 InitialConditions:
-  file_name:               fid.hdf5 # The file to read
+  file_name:               lowres8.hdf5 # The file to read
   periodic:                0    # Are we running with periodic ICs?
   stars_smoothing_length:  0.5
   

src/task.c

@@ -283,7 +283,6 @@ float task_overlap(const struct task *restrict ta,
     if (tb->ci != NULL) size_union += tb->ci->hydro.count;
     if (tb->cj != NULL) size_union += tb->cj->hydro.count;
 
-    // MATTHIEU: This should not be necessary
     if (size_union == 0) return 0.f;
 
     /* Compute the intersection of the cell data. */
@@ -305,6 +304,8 @@ float task_overlap(const struct task *restrict ta,
     if (tb->ci != NULL) size_union += tb->ci->grav.count;
     if (tb->cj != NULL) size_union += tb->cj->grav.count;
 
+    if (size_union == 0) return 0.f;
+
     /* Compute the intersection of the cell data. */
     const size_t size_intersect = task_cell_overlap_gpart(ta->ci, tb->ci) +
                                   task_cell_overlap_gpart(ta->ci, tb->cj) +