Fix possible nil deref in ogre (#1954)

Shouldn't normally happen, but we're also not doing
normal things :) Saw this happen in some testing.

Signed-off-by: Anders Eknert <anders.eknert@apple.com>

Author: anderseknert

internal/ogre/evaluator.go

@@ -81,6 +81,10 @@ func (e *Evaluator) Eval(ctx context.Context) (err error) {
 		return errNoResultHandler
 	}
 
+	if e.prepared == nil {
+		return errors.New("query must be prepared before eval")
+	}
+
 	store := e.prepared.store.store
 	txnProvided := e.txn != nil
 

internal/ogre/query.go

@@ -118,6 +118,10 @@ func (q *Query) Prepare(_ context.Context) (*Query, error) {
 		q.metrics = metrics.NoOp()
 	}
 
+	if q.store == nil {
+		q.store = NewStore()
+	}
+
 	// Compile all modules
 	q.compiler = q.newCompiler()
 
@@ -135,10 +139,6 @@ func (q *Query) Prepare(_ context.Context) (*Query, error) {
 		return nil, q.compiler.Errors
 	}
 
-	if q.store == nil {
-		q.store = NewStore()
-	}
-
 	return q, nil
 }