Merge pull request #73220 from mikeash/metadatasource-handle-null-source-6.0

[6.0][RemoteInspection] Ignore MetadataSource records with NULL source pointer.

Author: mikeash

include/swift/RemoteInspection/ReflectionContext.h

@@ -1989,6 +1989,9 @@ class ReflectionContext
   /// \param Builder Used to obtain offsets of elements known so far.
   bool isMetadataSourceReady(const MetadataSource *MS,
                              const RecordTypeInfoBuilder &Builder) {
+    if (!MS)
+      return false;
+
     switch (MS->getKind()) {
     case MetadataSourceKind::ClosureBinding:
       return true;