fix(form-input, form-textarea): handle case where input has been removed from document (closes #3498) (#3501)

Author: tmorehouse

src/mixins/form-text.js

@@ -122,9 +122,13 @@ export default {
         }
         // Update the v-model
         this.$emit('update', value)
-      } else if (value !== this.$refs.input.value) {
+      } else if (this.$refs.input && value !== this.$refs.input.value) {
         // When the `localValue` hasn't changed but the actual input value
-        // is out of sync, make sure to change it to the given one
+        // is out of sync, make sure to change it to the given one.
+        // Usually casued by browser autocomplete and how it triggers the
+        // change or input event, or depending on the formatter function.
+        // https://github.com/bootstrap-vue/bootstrap-vue/issues/2657
+        // https://github.com/bootstrap-vue/bootstrap-vue/issues/3498
         /* istanbul ignore next: hard to test */
         this.$refs.input.value = value
       }