Allow a ParseInfo without a script for %SetCode users

src/source-position.cc

Index: src/source-position.cc
diff --git a/src/source-position.cc b/src/source-position.cc
index ff204be73d327b2821646b77019badcff563d78d..02bb339357f3269e4cf65b57ee577e0a94c72838 100644
--- a/src/source-position.cc
+++ b/src/source-position.cc
@@ -11,10 +11,16 @@ namespace internal {
 
 std::ostream& operator<<(std::ostream& out, const SourcePositionInfo& pos) {
   Handle<SharedFunctionInfo> function(pos.function);
-  Handle<Script> script(Script::cast(function->script()));
+  String* name = nullptr;
+  if (function->script()->IsScript()) {
+    Script* script = Script::cast(function->script());
+    if (script->name()->IsString()) {
+      name = String::cast(script->name());
+    }
+  }
   out << "<";
-  if (script->name()->IsString()) {
-    out << String::cast(script->name())->ToCString(DISALLOW_NULLS).get();
+  if (name != nullptr) {
+    out << name->ToCString(DISALLOW_NULLS).get();
   } else {
     out << "unknown";
   }
@@ -78,12 +84,15 @@ std::vector<SourcePositionInfo> SourcePosition::InliningStack(
 
 void SourcePosition::Print(std::ostream& out,
                            SharedFunctionInfo* function) const {
-  Script* script = Script::cast(function->script());
-  Object* source_name = script->name();
   Script::PositionInfo pos;
-  script->GetPositionInfo(ScriptOffset(), &pos, Script::WITH_OFFSET);
+  Object* source_name = nullptr;
+  if (function->script()->IsScript()) {
+    Script* script = Script::cast(function->script());
+    source_name = script->name();
+    script->GetPositionInfo(ScriptOffset(), &pos, Script::WITH_OFFSET);
+  }
   out << "<";
-  if (source_name->IsString()) {
+  if (source_name != nullptr && source_name->IsString()) {
     out << String::cast(source_name)
                ->ToCString(DISALLOW_NULLS, ROBUST_STRING_TRAVERSAL)
                .get();
@@ -117,12 +126,14 @@ void SourcePosition::Print(std::ostream& out, Code* code) const {
 SourcePositionInfo::SourcePositionInfo(SourcePosition pos,
                                        Handle<SharedFunctionInfo> f)
     : position(pos), function(f) {
-  Handle<Script> script(Script::cast(function->script()));
-  Script::PositionInfo info;
-  if (Script::GetPositionInfo(script, pos.ScriptOffset(), &info,
-                              Script::WITH_OFFSET)) {
-    line = info.line;
-    column = info.column;
+  if (function->script()->IsScript()) {
+    Handle<Script> script(Script::cast(function->script()));
+    Script::PositionInfo info;
+    if (Script::GetPositionInfo(script, pos.ScriptOffset(), &info,
+                                Script::WITH_OFFSET)) {
+      line = info.line;
+      column = info.column;
+    }
   }
 }