fix dynamic form item validate bug (#1207)

examples/docs/en-US/form.md

@@ -122,7 +122,7 @@
         },
         dynamicForm: {
           domains: [{
-            key: 1,
+            key: Date.now(),
             value: ''
           }],
           email: ''
@@ -189,7 +189,7 @@
       },
       addDomain() {
         this.dynamicForm.domains.push({
-          key: this.dynamicForm.domains.length,
+          key: Date.now(),
           value: ''
         });
       }
@@ -819,6 +819,7 @@ Form component allows you to verify your data, helping you find and correct erro
 | label | label | string | — | — |
 | label-width | width of label, e.g. '50px' | string | — | — |
 | required | whether the field is required or not, will be determined by validation rules if omitted | string |  — | false |
+| rules | validation rules of form | object | — | — |
 
 
 

examples/docs/zh-CN/form.md

@@ -122,7 +122,7 @@
         },
         dynamicForm: {
           domains: [{
-            key: 1,
+            key: Date.now(),
             value: ''
           }],
           email: ''
@@ -189,7 +189,7 @@
       },
       addDomain() {
         this.dynamicForm.domains.push({
-          key: this.dynamicForm.domains.length,
+          key: Date.now(),
           value: ''
         });
       }
@@ -810,3 +810,4 @@
 | label | 标签文本 | string | — | — |
 | label-width | 表单域标签的的宽度，例如 '50px' | string |       —       | — |
 | required | 是否必填，如不设置，则会根据校验规则自动生成 | bolean | — | false |
+| rules    | 表单验证规则 | object | — | — |

packages/form/src/form.vue

@@ -36,8 +36,10 @@
       });
       /* istanbul ignore next */
       this.$on('el.form.removeField', (field) => {
-        delete this.fields[field.prop];
-        this.fieldLength--;
+        if (this.fields[field.prop]) {
+          delete this.fields[field.prop];
+          this.fieldLength--;
+        }
       });
     },
     methods: {