// Form Reset
export function resetForm(refName) {
    // The purpose of adding the if condition is to solve the problem of non-existent objects in the console
    if (this.$refs[refName] ) {
        this.$refs[refName].resetFields();
    }
}

Error Messages:

vue.runtime.esm.js?2b0e:1888 TypeError: Cannot read properties of undefined (reading 'indexOf')
    at VueComponent.resetField (element-ui.common.js?5c96:23528)
    at eval (element-ui.common.js?5c96:22945)
    at Array.forEach (<anonymous>)
    at VueComponent.resetFields (element-ui.common.js?5c96:22944)
    at VueComponent.resetForm (ruoyi.js?c38a:51)
    at VueComponent.reset (index.vue?6ced:2165)
    at VueComponent.handleCopy (index.vue?6ced:2504)
    at click (index.vue?e6ab:1003)
    at invokeWithErrorHandling (vue.runtime.esm.js?2b0e:1854)
    at VueComponent.invoker (vue.runtime.esm.js?2b0e:2179)

Solution:

// Form reset
export function resetForm(refName) {
// The purpose of adding the if condition is to solve the problem of non-existent objects in the console
    if (this.$refs[refName] !== undefined) {
        this.$refs[refName].resetFields();
    }
}

Another possibility for this type of problem is that the prop is not assigned a value, and a similar problem can occur:

 <el-form-item label="Self-pickup offer">
              <el-input
                v-model="form.selfOffer"
                :clearable="true"
                :disabled="disabled"
                placeholder="Please enter a discount price"
                @input="inputCityFloat"
              >
                <template slot="append">Yuan</template>
              </el-input>
            </el-form-item>