impl/memory: Disallow empty namespace.

service/datastore/context.go

Index: service/datastore/context.go
diff --git a/service/datastore/context.go b/service/datastore/context.go
index 165e3b0881bf5a69aaa7d08e624e9e24aaca5546..1fe5f8dddfe2a52c83f2968eac53ef61568ace08 100644
--- a/service/datastore/context.go
+++ b/service/datastore/context.go
@@ -64,10 +64,11 @@ func GetRawNoTxn(c context.Context) RawInterface {
 // Get gets the Interface implementation from context.
 func Get(c context.Context) Interface {
 	inf := info.Get(c)
+	ns, _ := inf.GetNamespace()
 	return &datastoreImpl{
 		GetRaw(c),
 		inf.FullyQualifiedAppID(),
-		inf.GetNamespace(),
+		ns,
 	}
 }
 
@@ -77,10 +78,11 @@ func Get(c context.Context) Interface {
 // Get gets the Interface implementation from context.
 func GetNoTxn(c context.Context) Interface {
 	inf := info.Get(c)
+	ns, _ := inf.GetNamespace()
 	return &datastoreImpl{
 		GetRawNoTxn(c),
 		inf.FullyQualifiedAppID(),
-		inf.GetNamespace(),
+		ns,
 	}
 }