stubgen: fix crash with PEP 604 union in typevar bound (#14557)

Fixes #14533

Author: hauntsaninja

mypy/stubgen.py

@@ -95,6 +95,7 @@
     MemberExpr,
     MypyFile,
     NameExpr,
+    OpExpr,
     OverloadedFuncDef,
     Statement,
     StrExpr,
@@ -402,6 +403,9 @@ def visit_list_expr(self, node: ListExpr) -> str:
     def visit_ellipsis(self, node: EllipsisExpr) -> str:
         return "..."
 
+    def visit_op_expr(self, o: OpExpr) -> str:
+        return f"{o.left.accept(self)} {o.op} {o.right.accept(self)}"
+
 
 class ImportTracker:
     """Record necessary imports during stub generation."""

test-data/unit/stubgen.test

@@ -2734,3 +2734,12 @@ class Some:
     def __int__(self) -> int: ...
     def __float__(self) -> float: ...
     def __index__(self) -> int: ...
+
+
+[case testTypeVarPEP604Bound]
+from typing import TypeVar
+T = TypeVar("T", bound=str | None)
+[out]
+from typing import TypeVar
+
+T = TypeVar('T', bound=str | None)