[f-spot] Check for existance of the key in cache dictionary first.

[Ruben Vermeersch <rubenv src gnome org>]

commit 105298b8f0f2f16d9ef77a35b4bbd90f2fee54b4
Author: Ruben Vermeersch <ruben savanne be>
Date:   Mon May 25 14:07:49 2009 +0200

    Check for existance of the key in cache dictionary first.
    
    Hashtable returned null, Dictionary throws an exception.
---
 src/Db.cs |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Db.cs b/src/Db.cs
index 750fc88..5ad854f 100644
--- a/src/Db.cs
+++ b/src/Db.cs
@@ -39,14 +39,14 @@ public abstract class DbStore<T> where T : DbItem {
 
 	protected T LookupInCache (uint id)
 	{
+		if (!item_cache.ContainsKey(id))
+			return null;
+
 		if (cache_is_immortal)
 			return item_cache [id] as T;
 
 		WeakReference weakref = item_cache [id] as WeakReference;
-		if (weakref == null)
-			return null;
-		else
-			return (T) weakref.Target;
+		return (T) weakref.Target;
 	}
 
 	protected void RemoveFromCache (T item)