Refactored Into 2 Code Paths

Refactored the code so that there is only a single branch for when there is one stored property and the rest return a SILType() as per @simonmpilkington suggestion.

Author: manavgabhawala

lib/IRGen/GenType.cpp

@@ -2031,13 +2031,9 @@ SILType irgen::getSingletonAggregateFieldType(IRGenModule &IGM,
 
     // If there's only one stored property, we have the layout of its field.
     auto allFields = structDecl->getStoredProperties();
-    auto field = allFields.begin();
-    // If there are no other fields exit early to prevent calling std::next on
-    // an invalid iterator.
-    if (allFields.empty())
-      return SILType();
 
-    if (std::next(field) == allFields.end())
+    auto field = allFields.begin();
+    if (!allFields.empty() && std::next(field) == allFields.end())
       return t.getFieldType(*field, *IGM.SILMod);
 
     return SILType();