fixup! fix tests

Author: charles-zablit

lldb/unittests/Platform/PlatformSiginfoTest.cpp

@@ -61,9 +61,10 @@ class PlatformSiginfoTest : public ::testing::Test {
     for (auto field_name : llvm::split(path, '.')) {
       uint64_t bit_offset;
       std::string name;
-      field_type = field_type.GetFieldAtIndex(
-          *field_type.GetIndexOfChildWithName(field_name, false), name,
-          &bit_offset, nullptr, nullptr);
+      auto index_or_err = field_type.GetIndexOfChildWithName(field_name, false);
+      ASSERT_TRUE(index_or_err);
+      field_type = field_type.GetFieldAtIndex(*index_or_err, name, &bit_offset,
+                                              nullptr, nullptr);
       ASSERT_TRUE(field_type);
       total_offset += bit_offset;
     }