将您的代码更改为...

import { defineStore } from 'pinia'
import axios from 'axios'

let serverHost = 'https://pokeapi.co/api/v2'

export const pokeStore = defineStore("pokemons", {
  state: () => {
    return {
      pokemons: []
    };
  },
  actions: {
    async getOnePokemon() {
      try {
        let id = Math.floor(Math.random() * 151) + 1; // <- I have changed this...
        let response = await axios.get(`${serverHost}/pokemon/${id}`)
        if(response.data){
          response.data.name = response.data.name.replace('-', " ");
          let pokemon = {
            id: response.data.id,
            name: response.data.name,
            image: response.data.sprites.front_default
          }
          if(!pokemon.image){
            pokemon.image = response.data.sprites.front_shiny
          }
          return pokemon
        }
      } catch (error) {
        console.log(error)
      }
    },
    
  }
});

你在catch中有一些代码，试图做随机id，但那不是应该去的地方。
我更新了在函数中生成随机id，而不是传入id。