Fix a crash

Author: DougGregor

lib/Sema/TypeCheckDecl.cpp

@@ -1107,7 +1107,8 @@ swift::computeAutomaticEnumValueKind(EnumDecl *ED) {
   // primitive literal protocols.
   auto conformsToProtocol = [&](KnownProtocolKind protoKind) {
     ProtocolDecl *proto = ED->getASTContext().getProtocol(protoKind);
-    return TypeChecker::conformsToProtocol(rawTy, proto, ED->getDeclContext());
+    return proto &&
+        TypeChecker::conformsToProtocol(rawTy, proto, ED->getDeclContext());
   };
 
   static auto otherLiteralProtocolKinds = {

validation-test/compiler_scale/enum_indirect.gyb

@@ -1,4 +1,4 @@
-// RUN: %scale-test --sum-multi --begin 5 --end 16 --step 5 --select InterfaceTypeRequest %s
+// RUN: %scale-test --sum-multi --begin 5 --end 15 --step 5 --select InterfaceTypeRequest %s
 // REQUIRES: asserts
 
 indirect enum Enum${N} {