Fix an issue with lazyness in the closure viewer

compiler/ghci/Linker.lhs

@@ -202,7 +202,9 @@ recoverDCInRTS a = do
 getHValue :: Name -> IO (Maybe HValue)
 getHValue name = do
     pls <- readIORef v_PersistentLinkerState
-    return$ fmap snd (lookupNameEnv (closure_env pls) name)
+    case lookupNameEnv (closure_env pls) name of
+      Just (_,x) -> return$ Just x
+      _          -> return Nothing
 
 withExtendedLinkEnv :: [(Name,HValue)] -> IO a -> IO a
 withExtendedLinkEnv new_env action

compiler/main/GHC.hs

@@ -2286,7 +2286,10 @@ mkSite (pkgName, modName, sitenum) =
   (mkModule (stringToPackageId pkgName) (mkModuleName modName), sitenum)
 
 obtainTerm :: Session -> Bool -> Id -> IO (Maybe Term)
-obtainTerm sess force id = withSession sess $ \hsc_env -> 
-              getHValue (varName id) >>= traverse (cvObtainTerm hsc_env force Nothing)
+obtainTerm sess force id = withSession sess $ \hsc_env -> do
+              mb_v <- getHValue (varName id) 
+              case mb_v of
+                Just v  -> fmap Just$ cvObtainTerm hsc_env force (Just$ idType id) v
+                Nothing -> return Nothing
 
 #endif /* GHCI */