temp fix to chainreader error when no workflows (#15678)

* temp fix to chainreader error when no workflows

* tidy

core/services/workflows/syncer/workflow_registry.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"iter"
+	"strings"
 	"sync"
 	"time"
 
@@ -222,8 +223,16 @@ func (w *workflowRegistry) Start(_ context.Context) error {
 			w.lggr.Debugw("Loading initial workflows for DON", "DON", don.ID)
 			loadWorkflowsHead, err := w.initialWorkflowsStateLoader.LoadWorkflows(ctx, don)
 			if err != nil {
-				w.lggr.Errorw("failed to load workflows", "err", err)
-				return
+				// TODO - this is a temporary fix to handle the case where the chainreader errors because the contract
+				// contains no workflows.  To track: https://smartcontract-it.atlassian.net/browse/CAPPL-393
+				if !strings.Contains(err.Error(), "attempting to unmarshal an empty string while arguments are expected") {
+					w.lggr.Errorw("failed to load workflows", "err", err)
+					return
+				}
+
+				loadWorkflowsHead = &types.Head{
+					Height: "0",
+				}
 			}
 
 			reader, err := w.getContractReader(ctx)