fix(Splitter): validate empty group silently (#2835)

* fix(Splitter): validate empty group silently

* fix(Splitter): keep panel-count invariant when validating empty group

---------

Co-authored-by: Lazizbek Ergashev <20501725+lazerg@users.noreply.github.com>

Author: lazerg

packages/core/src/Splitter/utils/validation.test.ts

@@ -0,0 +1,21 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { validatePanelGroupLayout } from './validation'
+
+afterEach(() => {
+  vi.restoreAllMocks()
+})
+
+describe('validatePanelGroupLayout', () => {
+  it('should validate an empty group silently', () => {
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {})
+    const result = validatePanelGroupLayout({ layout: [], panelConstraints: [] })
+    expect(result).toEqual([])
+    expect(warn).not.toHaveBeenCalled()
+  })
+
+  it('should throw when the layout length does not match the panel constraints', () => {
+    expect(() =>
+      validatePanelGroupLayout({ layout: [50, 50], panelConstraints: [] }),
+    ).toThrow('Invalid 0 panel layout')
+  })
+})

packages/core/src/Splitter/utils/validation.ts

@@ -12,6 +12,11 @@ export function validatePanelGroupLayout({
   panelConstraints: PanelConstraints[]
 }): number[] {
   const nextLayout = [...prevLayout]
+
+  // An empty group has no sizes to total, so 0 !== 100 here is not a misconfiguration
+  if (nextLayout.length === 0 && panelConstraints.length === 0)
+    return nextLayout
+
   const nextLayoutTotalSize = nextLayout.reduce(
     (accumulated, current) => accumulated + current,
     0,