effects.h: Fix missing implicitTrap for ArrayRMW and ArrayCmpxchg (#8328)

- `visitArrayRMW` and `visitArrayCmpxchg` in `EffectAnalyzer` only set
`implicitTrap` when the array reference is nullable, missing the
out-of-bounds index case.

Author: sumleo

src/ir/effects.h

@@ -1027,9 +1027,8 @@ class EffectAnalyzer {
       }
       parent.readsArray = true;
       parent.writesArray = true;
-      if (curr->ref->type.isNullable()) {
-        parent.implicitTrap = true;
-      }
+      // traps when the arg is null or the index out of bounds
+      parent.implicitTrap = true;
       assert(curr->order != MemoryOrder::Unordered);
       parent.isAtomic = true;
     }
@@ -1040,9 +1039,8 @@ class EffectAnalyzer {
       }
       parent.readsArray = true;
       parent.writesArray = true;
-      if (curr->ref->type.isNullable()) {
-        parent.implicitTrap = true;
-      }
+      // traps when the arg is null or the index out of bounds
+      parent.implicitTrap = true;
       assert(curr->order != MemoryOrder::Unordered);
       parent.isAtomic = true;
     }