component storage issue diagnosed and fixed

it was because in the handling of removing components, we would swap
components within the storage. then we would update the entity's
componentid list so that the removed component ref would be removed, and
that the component ref pointing to the item that was swapped be updated
to point at the new correct index within storage. this part was fine,
but when updating the component id refs, we forgot to check that the
componentid component storage type (base, updatable, renderable) when
finding the componentid pointing to the moved component in storage.

source/re/ecs/storage.d

@@ -180,8 +180,9 @@ class ComponentStorage {
 
         // - update storage
         auto storage = get_storage(id);
-        writefln("REMOVING component_type: %s AT %d", to!string(id.type), id.index);
-        writefln("storage[%d]: %s", storage.length, storage.array);
+        auto storage_type = id.type;
+        // writefln("REMOVING component_type: %s AT %d", to!string(id.type), id.index);
+        // writefln("storage[%d]: %s", storage.length, storage.array);
 
         // empty the slot, and swap it to the end
         assert(id.index < storage.length, format("id points to invalid position (%d) in %s storage",
@@ -197,18 +198,23 @@ class ComponentStorage {
             // handle swapping our nulled slot with the last slot
             auto tmp = storage[last_slot];
             assert(tmp, "storage tail slot is null");
-            assert(tmp.entity, "entity in tail slot is null");
+            assert(tmp.entity, "entity in tail slot is null. this means that"
+                    ~ " the component doesn't have an assocated entity");
             storage[last_slot] = storage[id.index];
             storage[id.index] = tmp;
-            writefln("swapped SLOT (%d) with TAIL (%d)", id.index, last_slot);
+            // the entity we are removing has been swapped with the last slot
+            // writefln("swapped SLOT (%d) with TAIL (%d)", id.index, last_slot);
             // find out who owns tmp, and tell them that their component has moved
             auto other = tmp.entity;
             // find the id that points to the old place
-            auto other_id_pos = other.components.countUntil!(x => x.index == last_slot);
-            writefln("working with OTHER, components %s", other.components);
-            writefln("(%s) updating COMPREF from OLDSLOT (%d) to NEWSLOT (%d)", other.name, other
-                    .components[other_id_pos].index, id.index);
+            // to find it, it has an index pointing to the last slot (because it was swapped, so the component was previously there)
+            // we also need to be sure to be searching the correct storage type
+            auto other_id_pos = other.components.countUntil!(x => x.type == storage_type && x.index == last_slot);
+            // writefln("working with OTHER, components %s", other.components);
+            // writefln("(%s) updating COMPREF from OLDSLOT (%d) to NEWSLOT (%d)", other.name, other
+            //         .components[other_id_pos].index, id.index);
             other.components[other_id_pos].index = id.index; // point to the new place
+            // writefln("OTHER components result: %s", other.components);
         }
         // pop the last element off the array
         storage = storage.remove(last_slot);
@@ -280,23 +286,23 @@ unittest {
     writefln("all components: %s", storage.get_all(nt));
     auto thing1s = storage.get_all!Thing1(nt);
     assert(thing1s.length == 6, format("expected 6 thing1s, got %d", thing1s.length));
-    writefln("match thing1s passed: %s", thing1s);
+    // writefln("match thing1s passed: %s", thing1s);
 
     auto thing2s = storage.get_all!Thing2(nt);
     assert(thing2s.length == 4, format("expected 4 thing2s, got %d", thing2s.length));
-    writefln("match thing2s passed: %s", thing2s);
+    // writefln("match thing2s passed: %s", thing2s);
 
     // try removing random stuff
     manual_nt_remove(nt, thing13);
     manual_nt_remove(nt, thing11);
     thing1s = storage.get_all!Thing1(nt);
     assert(thing1s.length == 4, format("expected 4 thing1s, got %d", thing1s.length));
-    writefln("expected-1 thing1s passed: %s", thing1s);
+    // writefln("expected-1 thing1s passed: %s", thing1s);
 
     manual_nt_remove(nt, thing22);
     thing2s = storage.get_all!Thing2(nt);
     assert(thing2s.length == 3, format("expected 3 thing2s, got %d", thing2s.length));
-    writefln("expected-2 thing2s passed: %s", thing2s);
+    // writefln("expected-2 thing2s passed: %s", thing2s);
 }
 
 @("ecs-storage-types")