Add guards for parent field in QAutocomplete and watch noParentField (quasarframework#1956)

Author: pdanpdan

src/components/autocomplete/QAutocomplete.js

@@ -192,7 +192,9 @@ export default {
       this.__inputDebounce.setChildDebounce(true)
     }
     this.$nextTick(() => {
-      this.inputEl = this.__input.getEl()
+      if (this.__input) {
+        this.inputEl = this.__input.getEl()
+      }
       this.inputEl.addEventListener('keydown', this.__keyboardHandleKey)
       this.inputEl.addEventListener('blur', this.blurHide)
     })

src/mixins/parent-field.js

@@ -8,6 +8,14 @@ export default {
   props: {
     noParentField: Boolean
   },
+  watch: {
+    noParentField (val) {
+      if (!this.field) {
+        return
+      }
+      this.field[val ? '__registerInput' : '__unregisterInput'](this)
+    }
+  },
   beforeMount () {
     if (!this.noParentField && this.field) {
       this.field.__registerInput(this)