Create missing path elements

This fixes a serious error: trying to change a value on gui.someOption would add
a someOption key at root if gui doesn't exist.

pkg/utils/yaml_utils/yaml_utils.go

@@ -64,12 +64,26 @@ func updateYamlNode(node *yaml.Node, path []string, value string) error {
 	}
 
 	// if the key doesn't exist, we'll add it
+
+	// at end of path: add the new key, done
+	if len(path) == 1 {
+		node.Content = append(node.Content, &yaml.Node{
+			Kind:  yaml.ScalarNode,
+			Value: key,
+		}, &yaml.Node{
+			Kind:  yaml.ScalarNode,
+			Value: value,
+		})
+		return nil
+	}
+
+	// otherwise, create the missing intermediate node and continue
+	newNode := &yaml.Node{
+		Kind: yaml.MappingNode,
+	}
 	node.Content = append(node.Content, &yaml.Node{
 		Kind:  yaml.ScalarNode,
 		Value: key,
-	}, &yaml.Node{
-		Kind:  yaml.ScalarNode,
-		Value: value,
-	})
-	return nil
+	}, newNode)
+	return updateYamlNode(newNode, path[1:], value)
 }

pkg/utils/yaml_utils/yaml_utils_test.go

@@ -56,6 +56,14 @@ func TestUpdateYamlValue(t *testing.T) {
 			expectedOut: "foo:\n    bar: qux\n",
 			expectedErr: "",
 		},
+		{
+			name:        "nested where parents doesn't exist yet",
+			in:          "",
+			path:        []string{"foo", "bar", "baz"},
+			value:       "qux",
+			expectedOut: "foo:\n    bar:\n        baz: qux\n",
+			expectedErr: "",
+		},
 
 		// Error cases
 		{