Fix: Set does not update the model within the database

see title

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

controller/nucleus/principalNetworkDomain.go

@@ -153,6 +153,9 @@ func (pnd *pndImplementation) Commit(u uuid.UUID) error {
 		return err
 	}
 	diff, err := ygot.Diff(ch.PreviousState(), ch.IntendedState())
+	if err != nil {
+		return err
+	}
 	for _, update := range diff.GetUpdate() {
 		opts := []ytypes.SetNodeOpt{&ytypes.InitMissingElements{}, &ytypes.TolerateJSONInconsistencies{}}
 		if err := ytypes.SetNode(networkElement.SBI().Schema().RootSchema(), networkElement.GetModel(), update.GetPath(), update.GetVal(), opts...); err != nil {