fix: nil pointer on bgp

Fixes #207

routeros/mikrotik_serialize.go

@@ -214,6 +214,11 @@ func TerraformResourceDataToMikrotik(s map[string]*schema.Schema, d *schema.Reso
 					filedNameInState := fmt.Sprintf("%v.%v.%v", terraformSnakeName, 0, fieldName)
 					fieldSchema := terraformMetadata.Elem.(*schema.Resource).Schema[fieldName]
 
+					// Skip all read-only properties.
+					if fieldSchema.Computed && !fieldSchema.Optional {
+						continue
+					}
+
 					if fieldSchema.Optional && !d.HasChange(filedNameInState) &&
 						isEmpty(filedNameInState, fieldSchema, d, ctyList.GetAttr(fieldName)) {
 						continue
@@ -378,6 +383,16 @@ func MikrotikResourceDataToTerraform(item MikrotikItem, s map[string]*schema.Sch
 				case *schema.Resource:
 					var v any
 
+					if _, ok := s[terraformSnakeName].Elem.(*schema.Resource).Schema[subFieldSnakeName]; !ok {
+						diags = append(diags, diag.Diagnostic{
+							Severity: diag.Warning,
+							Summary:  "Field '" + terraformSnakeName + "." + subFieldSnakeName + "' not found in the schema",
+							Detail: fmt.Sprintf("[MikrotikResourceDataToTerraformDatasource] the datasource Schema sub-field was lost during development: ▷ '%s.%s' ◁",
+								terraformSnakeName, subFieldSnakeName),
+						})
+						continue
+					}
+
 					switch s[terraformSnakeName].Elem.(*schema.Resource).Schema[subFieldSnakeName].Type {
 					case schema.TypeString:
 						v = mikrotikValue

routeros/resource_bgp_connection.go

@@ -278,6 +278,11 @@ func ResourceRoutingBGPConnection() *schema.Resource {
 						Optional:    true,
 						Description: "Local connection IPv4/6 address.",
 					},
+					"default_address": {
+						Type:        schema.TypeString,
+						Computed:    true,
+						Description: "",
+					},
 					"port": {
 						Type:         schema.TypeInt,
 						Optional:     true,