fix mypy errs

Author: BobTheBuidler

mypyc/irbuild/constant_fold.py

@@ -89,7 +89,7 @@ def constant_fold_expr(builder: IRBuilder, expr: Expression) -> ConstantValue |
                 and isinstance(arg := args[0], (ListExpr, TupleExpr))
             ):
                 folded_items = constant_fold_container_expr(builder, arg)
-                if all(isinstance(item, str) for item in folded_items):
+                if folded_items is not None and all(isinstance(item, str) for item in folded_items):
                     return folded_callee.join(folded_items)
 
         # builtins.bytes methods
@@ -102,7 +102,7 @@ def constant_fold_expr(builder: IRBuilder, expr: Expression) -> ConstantValue |
                 and isinstance(arg := args[0], (ListExpr, TupleExpr))
             ):
                 folded_items = constant_fold_container_expr(builder, arg)
-                if all(isinstance(item, bytes) for item in folded_items):
+                if folded_items is not None and all(isinstance(item, bytes) for item in folded_items):
                     return folded_callee.join(folded_items)
     return None
 
@@ -139,7 +139,7 @@ def constant_fold_container_expr(
     builder: IRBuilder, expr: ListExpr | TupleExpr
 ) -> list[ConstantValue] | tuple[ConstantValue, ...] | None:
     folded_items = [constant_fold_expr(builder, item_expr) for item_expr in expr.items]
-    if all(isinstance(item, (ConstantValue)) for item in folded_items):
+    if all(isinstance(item, CONST_TYPES) for item in folded_items):
         if isinstance(expr, ListExpr):
             return folded_items
         elif isinstance(expr, TupleExpr):