[Swift] lldb: Adjust code after result type change in lldb_private::formatters::ExtractIndexFromString

See llvm#138297

(cherry picked from commit 250d993)

Author: AnthonyLatsis

lldb/source/Plugins/Language/Swift/SwiftArray.cpp

@@ -559,11 +559,12 @@ llvm::Expected<size_t> lldb_private::formatters::swift::ArraySyntheticFrontEnd::
     return llvm::createStringError("Type has no child named '%s'",
                                    name.AsCString());
   const char *item_name = name.GetCString();
-  uint32_t idx = ExtractIndexFromString(item_name);
-  if (idx == UINT32_MAX || idx >= CalculateNumChildrenIgnoringErrors())
+  auto optional_idx = ExtractIndexFromString(item_name);
+  if (!optional_idx ||
+      optional_idx.value() >= CalculateNumChildrenIgnoringErrors())
     return llvm::createStringError("Type has no child named '%s'",
                                    name.AsCString());
-  return idx;
+  return optional_idx.value();
 }
 
 SyntheticChildrenFrontEnd *

lldb/source/Plugins/Language/Swift/SwiftHashedContainer.cpp

@@ -747,9 +747,10 @@ HashedSyntheticChildrenFrontEnd::GetIndexOfChildWithName(ConstString name) {
     return llvm::createStringError("Type has no child named '%s'",
                                    name.AsCString());
   const char *item_name = name.GetCString();
-  uint32_t idx = ExtractIndexFromString(item_name);
-  if (idx == UINT32_MAX || idx >= CalculateNumChildrenIgnoringErrors())
+  auto optional_idx = ExtractIndexFromString(item_name);
+  if (!optional_idx ||
+      optional_idx.value() >= CalculateNumChildrenIgnoringErrors())
     return llvm::createStringError("Type has no child named '%s'",
                                    name.AsCString());
-  return idx;
+  return optional_idx.value();
 }