[Alerting UI] Fix console error when setting connector params (#83333)

* Fixing console errors

* Setting defaults for undefined inputs in text area/field with message variables

* Cleanup

* Cleanup

* Fixing pagerduty timestamp validation

* Fixing test

* Pagerduty params

* Reverting unnecessary changes

Author: ymao1

x-pack/plugins/triggers_actions_ui/public/application/components/text_area_with_message_variables.tsx

@@ -63,7 +63,7 @@ export const TextAreaWithMessageVariables: React.FunctionComponent<Props> = ({
         fullWidth
         isInvalid={errors && errors.length > 0 && inputTargetValue !== undefined}
         name={paramsProperty}
-        value={inputTargetValue}
+        value={inputTargetValue || ''}
         data-test-subj={`${paramsProperty}TextArea`}
         onChange={(e: React.ChangeEvent<HTMLTextAreaElement>) => onChangeWithMessageVariable(e)}
         onFocus={(e: React.FocusEvent<HTMLTextAreaElement>) => {

x-pack/plugins/triggers_actions_ui/public/application/components/text_field_with_message_variables.tsx

@@ -50,7 +50,7 @@ export const TextFieldWithMessageVariables: React.FunctionComponent<Props> = ({
       id={`${paramsProperty}Id`}
       isInvalid={errors && errors.length > 0 && inputTargetValue !== undefined}
       data-test-subj={`${paramsProperty}Input`}
-      value={inputTargetValue}
+      value={inputTargetValue || ''}
       onChange={(e: React.ChangeEvent<HTMLInputElement>) => onChangeWithMessageVariable(e)}
       onFocus={(e: React.FocusEvent<HTMLInputElement>) => {
         setCurrentTextElement(e.target);

x-pack/plugins/triggers_actions_ui/public/application/sections/action_connector_form/connector_add_flyout.tsx

@@ -72,10 +72,8 @@ export const ConnectorAddFlyout = ({
   const [isSaving, setIsSaving] = useState<boolean>(false);
 
   const closeFlyout = useCallback(() => {
-    setActionType(undefined);
-    setConnector(initialConnector);
     onClose();
-  }, [onClose, initialConnector]);
+  }, [onClose]);
 
   const canSave = hasSaveActionsCapability(capabilities);