[lldb] Add a missing check for an empty array

rdar://152611562

Author: adrian-prantl

lldb/source/Plugins/LanguageRuntime/Swift/SwiftLanguageRuntimeDynamicTypeResolution.cpp

@@ -1456,6 +1456,8 @@ SwiftRuntimeTypeVisitor::VisitImpl(std::optional<unsigned> visit_only,
         ++i;
       }
     }
+    if (supers.empty())
+      return llvm::createStringError("could not get instance type info");
 
     // Handle the "real" fields.
     auto *object = supers[0].get_record_type_info();

lldb/test/API/lang/swift/foundation_value_types/notification/TestSwiftFoundationTypeNotification.py

@@ -32,3 +32,7 @@ def test(self):
                     substrs=['name = ', '"MyNotification"',
                              'object = nil',
                              'userInfo = 0 key/value pairs'])
+        name = self.frame().FindVariable("name")
+        # This is a "don't crash" test.
+        child = name.GetChildAtIndex(0)
+        self.assertEquals(name.GetSummary(), '"MyNotification"')

lldb/test/API/lang/swift/foundation_value_types/notification/main.swift

@@ -1,7 +1,8 @@
 import Foundation
 
 func main() {
-  var notification = Notification(name: Notification.Name(rawValue: "MyNotification"), object: nil, userInfo: [:])
+  var name = Notification.Name(rawValue: "MyNotification")
+  var notification = Notification(name: name, object: nil, userInfo: [:])
   print("break here!")
 }