Handle 'not supplied' case for field type TypeNameString (#3546)

* Fix panic if value is not supplied for variables of TypeNameString

* Add tests for 'not supplied' case of all field types

logical/framework/backend.go

@@ -604,6 +604,8 @@ func (s *FieldSchema) DefaultOrZero() interface{} {
 // Zero returns the correct zero-value for a specific FieldType
 func (t FieldType) Zero() interface{} {
 	switch t {
+	case TypeNameString:
+		return ""
 	case TypeString:
 		return ""
 	case TypeInt:

logical/framework/field_data_test.go

@@ -278,6 +278,87 @@ func TestFieldDataGet(t *testing.T) {
 			"foo",
 			"bar.baz-bay123",
 		},
+
+		"name string type, not supplied": {
+			map[string]*FieldSchema{
+				"foo": {Type: TypeNameString},
+			},
+			map[string]interface{}{},
+			"foo",
+			"",
+		},
+
+		"string type, not supplied": {
+			map[string]*FieldSchema{
+				"foo": {Type: TypeString},
+			},
+			map[string]interface{}{},
+			"foo",
+			"",
+		},
+
+		"type int, not supplied": {
+			map[string]*FieldSchema{
+				"foo": {Type: TypeInt},
+			},
+			map[string]interface{}{},
+			"foo",
+			0,
+		},
+
+		"type bool, not supplied": {
+			map[string]*FieldSchema{
+				"foo": {Type: TypeBool},
+			},
+			map[string]interface{}{},
+			"foo",
+			false,
+		},
+
+		"type map, not supplied": {
+			map[string]*FieldSchema{
+				"foo": {Type: TypeMap},
+			},
+			map[string]interface{}{},
+			"foo",
+			map[string]interface{}{},
+		},
+
+		"type duration second, not supplied": {
+			map[string]*FieldSchema{
+				"foo": {Type: TypeDurationSecond},
+			},
+			map[string]interface{}{},
+			"foo",
+			0,
+		},
+
+		"type slice, not supplied": {
+			map[string]*FieldSchema{
+				"foo": {Type: TypeSlice},
+			},
+			map[string]interface{}{},
+			"foo",
+			[]interface{}{},
+		},
+
+		"type string slice, not supplied": {
+			map[string]*FieldSchema{
+				"foo": {Type: TypeStringSlice},
+			},
+			map[string]interface{}{},
+			"foo",
+			[]string{},
+		},
+
+		"type comma string slice, not supplied": {
+			map[string]*FieldSchema{
+				"foo": {Type: TypeCommaStringSlice},
+			},
+			map[string]interface{}{},
+			"foo",
+			[]string{},
+		},
 	}
 
 	for name, tc := range cases {