fix(b-modal): delay initially open modal via nextTick when using v-mo…

…del or visible prop (#3320)

* fix(modal): delay initially open modal via nextTick when using v-model or visible prop


When modal is set to be initially open on mount, delay the show in a `$nextTick()` to ensure DOM is fully loaded

Addresses #3312 (comment)

* Update modal.js

* Update modal.js

src/components/modal/modal.js

@@ -343,7 +343,7 @@ export default Vue.extend({
     this.listenOnRoot('bv::modal::show', this.modalListener)
     // Initially show modal?
     if (this.visible === true) {
-      this.show()
+      this.$nextTick(this.show)
     }
   },
   beforeDestroy() {
@@ -401,7 +401,7 @@ export default Vue.extend({
       // Show the modal
       this.doShow()
     },
-    hide(trigger) {
+    hide(trigger = '') {
       if (!this.is_visible || this.is_closing) {
         /* istanbul ignore next */
         return