experimental: Fix inset reset (onAbort is called on blur) (#5105)

## Description

1. What is this PR about (link the issue and add a short description)

## Steps for reproduction

1. click button
2. expect xyz

## Code Review

- [ ] hi @kof, I need you to do
  - conceptual review (architecture, feature-correctness)
  - detailed review (read every line)
  - test it on preview

## Before requesting a review

- [ ] made a self-review
- [ ] added inline comments where things may be not obvious (the "why",
not "what")

## Before merging

- [ ] tested locally and on preview environment (preview dev login:
0000)
- [ ] updated [test
cases](https://github.com/webstudio-is/webstudio/blob/main/apps/builder/docs/test-cases.md)
document
- [ ] added tests
- [ ] if any new env variables are added, added them to `.env` file

Author: istarkov

apps/builder/app/builder/features/settings-panel/props-section/animation/animation-section.tsx

@@ -389,13 +389,23 @@ export const AnimationSection = ({
               id={fieldIds.insetStart}
               value={value.insetStart ?? { type: "keyword", value: "auto" }}
               onChange={(insetStart, isEphemeral) => {
+                if (insetStart === undefined) {
+                  handleChange(undefined, isEphemeral);
+                  return;
+                }
+
                 handleChange({ ...value, insetStart }, isEphemeral);
               }}
             />
             <InsetValueInput
               id={fieldIds.insetEnd}
               value={value.insetEnd ?? { type: "keyword", value: "auto" }}
               onChange={(insetEnd, isEphemeral) => {
+                if (insetEnd === undefined) {
+                  handleChange(undefined, isEphemeral);
+                  return;
+                }
+
                 handleChange({ ...value, insetEnd }, isEphemeral);
               }}
             />