detect when switch on error shadows it's own switch case capture

lib/std/zig/AstGen.zig

@@ -7693,7 +7693,7 @@ fn switchExpr(
                 payload_sub_scope = switch_scope;
             } else {
                 const capture_name = try astgen.identAsString(ident);
-                try astgen.detectLocalShadowing(&scratch_scope.base, capture_name, ident, ident_slice, .capture);
+                try astgen.detectLocalShadowing(switch_scope, capture_name, ident, ident_slice, .capture);
                 payload_capture_scope = .{
                     .parent = switch_scope,
                     .gen_zir = &scratch_scope,

test/cases/compile_errors/switch_on_error_shadows_case_capture.zig

@@ -0,0 +1,24 @@
+export fn entry1() void {
+    const e: error{Foo}!u32 = error.Foo;
+    e catch |err| switch (err) {
+        error.Foo => |err| {
+            _ = err catch {};
+        },
+    };
+}
+
+export fn entry2() void {
+    const e: error{Foo}!u32 = error.Foo;
+    if (e) {} else |err| switch (err) {
+        error.Foo => |err| {
+            _ = err catch {};
+        },
+    }
+}
+
+// error
+//
+// :4:23: error: redeclaration of capture 'err'
+// :3:14: note: previous declaration here
+// :13:23: error: redeclaration of capture 'err'
+// :12:21: note: previous declaration here