Fix crash in refactoring checker from unaryop with variable

doc/whatsnew/fragments/9074.bugfix

@@ -0,0 +1,3 @@
+Fix crash in refactoring checker when unary operand used with variable in for loop.
+
+Closes #9074

pylint/checkers/refactoring/refactoring_checker.py

@@ -2362,7 +2362,7 @@ def _get_start_value(self, node: nodes.NodeNG) -> tuple[int | None, Confidence]:
         if (
             isinstance(node, (nodes.Name, nodes.Call, nodes.Attribute))
             or isinstance(node, nodes.UnaryOp)
-            and isinstance(node.operand, nodes.Attribute)
+            and isinstance(node.operand, (nodes.Attribute, nodes.Name))
         ):
             inferred = utils.safe_infer(node)
             start_val = inferred.value if inferred else None

tests/functional/r/regression/regression_9074_refactor_loop_with_unary_variable.py

@@ -0,0 +1,7 @@
+"""Regression test."""
+def crash_on_unary_op_with_name():
+    """Should not crash with -idx."""
+    mylist = []
+    idx = 5
+    for _i, _val in enumerate(mylist, start=-idx):
+        pass