要正确打包，需要将`node_modules/bpmn-engine/index.js`中的
`const BpmnModdle = require('bpmn-moddle');`改为：
`const BpmnModdle = require('bpmn-moddle').default;`

在
bpmn-elements/dist/tasks/LoopCharacteristics.js from line 169:
```
ParallelLoopCharacteristics.prototype._onCompleteMessage = function onCompleteMessage(routingKey, message) {
const chr = this.characteristics;
const {
content
} = message;
if (content.output !== undefined) chr.output[content.index] = content.output;
if (routingKey === 'execute.discard') {
this.discarded++;
}
this.running--;
this.activity.broker.publish('execution', 'execute.iteration.completed', {
...content,
...chr.getContent(),
index: this.index,                    // >>>>>>>  这行要删除
running: this.running,
discarded: this.discarded,
output: chr.output,
state: 'iteration.completed',
preventComplete: true
});
```