fix: address code review findings

internal/cache/store.go

@@ -270,13 +270,13 @@ func (c *CacheAside) Delete(ctx context.Context, key *CacheKey) error {
 // Get retrieves a value from cache by key.
 func (c *CacheAside) Get(ctx context.Context, key *CacheKey) ([]byte, error) {
 	val, err := c.store.Get(ctx, key)
-	if errors.Is(err, redis.Nil) {
-		c.metrics.RecordCacheMiss("cache_aside") // record cache aside miss
-		return nil, nil // cache miss
-	}
 	if err != nil {
 		return nil, fmt.Errorf("cache get: %w", err)
 	}
+	if val == nil {
+		c.metrics.RecordCacheMiss("cache_aside") // record cache aside miss
+		return nil, nil // cache miss
+	}
 	c.metrics.RecordCacheHit("cache_aside") // record cache aside hit
 	return val, nil
 }