fix: support array of structs in abi.decode

slither/visitors/slithir/expression_to_slithir.py

@@ -448,12 +448,12 @@ def _post_index_access(self, expression: IndexAccess) -> None:
         right = get(expression.expression_right)
         operation: Operation
         # Left can be a type for abi.decode(var, uint[2])
-        if isinstance(left, (Type, Contract, Enum)):
+        if isinstance(left, (Type, Contract, Enum, Structure)):
             # Nested type are not yet supported by abi.decode, so the assumption
             # Is that the right variable must be a constant
             assert isinstance(right, Constant)
             # Case for abi.decode(var, I[2]) where I is an interface/contract or an enum
-            if isinstance(left, (Contract, Enum)):
+            if isinstance(left, (Contract, Enum, Structure)):
                 left = UserDefinedType(left)
             t = ArrayType(left, int(right.value))
             set_val(expression, t)