Handle errors when processing wizard steps

Closes #13906
(grafted from ab4ac9e315c67207a0855e4314689260ab0b59ba)

--HG--
branch : 6.0

sao/src/rpc.js

@@ -97,7 +97,9 @@
                     }
                 } else {
                     Sao.common.error.run(data.error[0], data.error[1])
-                        .always(dfd.reject);
+                        .always(function() {
+                            dfd.reject(data.error);
+                        });
                 }
             } else {
                 result = data.result;

sao/src/wizard.js

@@ -106,7 +106,10 @@
                     }
                     this.__processing = false;
                 }.bind(this), function(result) {
-                    // TODO end for server error.
+                    if (!result || !this.screen) {
+                        this.state = this.end_state;
+                        this.end();
+                    }
                     this.__processing = false;
                 }.bind(this));
             };