At first, I thought Syntax Error was node_modules and there was another problem, so I violently deleted the node_modules folder, and then back up in the backup file. It turned out to be useless. This is a grammatical error.
Then I continued to search for information, so I found the problem on CSDN blogger: Rabbit Gone away [click to open link].
In the HTML tag, one v-model bound property value is not declared .
So the problem was solved instantly, and I read back the wrong information afterwards, which actually gave me a very clear wrong position. As shown in figure:

It seems that we still need more observation, careful deBug ah…