title: VueBootstrap and New VeeValidate can't make custom modal
body: <p>Hello I have in my component this modal:</p>
  
  <pre><code>    &lt;b-modal title="title" v-model="modal_show" v-if="modal_show" &gt;
         &lt;ValidationObserver v-slot="{ invalid }"&gt;   
            &lt;b-container fluid&gt;
               &lt;ValidationProvider rules="minVal:0.1" v-slot="{ errors, valid }" name="quantità"&gt;
                  &lt;b-form-input id="quantity" name="quantity"
                      v-model="productEdited.quantity" type="text" 
                      class="form-control" /&gt;
                  &lt;div class="invalid-feedback d-block"&gt;
                     &lt;span&gt;{{errors[0]}}&lt;/span&gt;
                  &lt;/div&gt;
               &lt;/ValidationProvider&gt;
            &lt;/b-container&gt;
           &lt;template v-slot:modal-footer&gt;
              &lt;b-button class="mt-3 float-right" variant="outline-danger" @click="toggleModal"&gt;close&lt;/b-button&gt;
              &lt;b-button class="mt-3 float-right" variant="outline-warning"  @click="updateProductInOrder" :disabled="invalid"&gt;save&lt;/b-button&gt;
           &lt;/template&gt;
        &lt;/ValidationObserver&gt;
     &lt;/b-modal&gt;
  </code></pre>
  
  <p>But I can't compile with this error:</p>
  
  <blockquote>
    <p>To avoid scope ambiguity, the default slot should also use 
    syntax when there are other named slots.</p>
  </blockquote>
  
  <p>My problem is that :</p>
  
  <p>I would like disable "submit" button in realtime with validation and also I would like override footer modal template of vue-bootstrap modal.</p>
  
  <p>If I put  <strong></strong> outisde <strong></strong> I can compile, but I can't disabled button with <strong>ValidationObserver valid</strong> slot.
  I have create also a codeSandBox.</p>
  
  <p><a href="https://codesandbox.io/embed/vue-template-o4vkk?fontsize=14" rel="nofollow noreferrer">https://codesandbox.io/embed/vue-template-o4vkk?fontsize=14</a></p>
  
  <p>What I'm wrong?</p>