Emit ApiErrorOccurred metric for request timed out error

Author: m-Peter

api/server.go

@@ -435,7 +435,10 @@ type responseHandler struct {
 	metrics     metrics.Collector
 }
 
-const errCodePanic = -32603
+const (
+	errCodePanic   = -32603
+	errCodeTimeout = -32002
+)
 
 type jsonError struct {
 	Code    int    `json:"code"`
@@ -470,6 +473,11 @@ func (w *responseHandler) Write(data []byte) (int, error) {
 		w.metrics.ServerPanicked(message.Error.Message)
 	}
 
+	// handle possible request timeouts
+	if message.Error != nil && message.Error.Code == errCodeTimeout {
+		w.metrics.ApiErrorOccurred()
+	}
+
 	// It's an error response and requires special treatment.
 	if message.Error != nil {
 		// The logic below is taken from: