This type of error occur when you try to push data in array and you have not declare that variable as [] type .
Example :
image = ' ';
this.image.push({label:'testImage'});
The above code may give you following error .
The simplest way to solve this error is declare your with proper data type.
image = [];
this.image.push({label:'testImage'});
If you have found some another solution for the given issue then please post in comment section that may help other coders to save their time.