Fix panic building policy (#243)

This commit fixes a panic creating policies for repos with controls enabled

Signed-off-by: Adolfo Garcia Veytia (puerco) <[email protected]>

Author: puerco

sourcetool/pkg/slsa/slsa_types.go

@@ -66,6 +66,9 @@ type Controls []*provenance.Control
 // Adds the control to the list. Ignores nil controls.
 // Does not check for duplicate controls.
 func (controls *Controls) AddControl(newControls ...*provenance.Control) {
+	if controls == nil {
+		controls = &Controls{}
+	}
 	for _, c := range newControls {
 		if c == nil {
 			continue

sourcetool/pkg/sourcetool/tool.go

@@ -204,13 +204,12 @@ func (t *Tool) CreateBranchPolicy(ctx context.Context, r *models.Repository, bra
 		return nil, fmt.Errorf("could not get provenance for latest commit: %w", err)
 	}
 
-	var controls *slsa.Controls
+	controls := &slsa.Controls{}
 	if predicate != nil {
 		for _, c := range predicate.GetControls() {
 			controls.AddControl(c)
 		}
 	}
-
 	return t.createPolicy(r, branches[0], controls)
 }