fix(core): correct element removal order in unsets (#556)

When unsetting multiple array elements using range expressions, elements
were being removed in forward order causing index shifting issues. This
resulted in subsequent removals targeting incorrect indices.

Now processes unset matches in reverse order to maintain index stability
during removal, ensuring correct behavior for range operations like
`items[1:3]`.

Fixes array unset operations that were removing wrong elements due to
index shifting during the removal process.

Author: ricokahler

packages/core/src/document/patchOperations.test.ts

@@ -668,7 +668,7 @@ describe('unset', () => {
   it('unsets multiple array elements when using a range', () => {
     const input = {items: [1, 2, 3, 4, 5]}
     const output = unset(input, ['items[1:3]'])
-    expect(output).toEqual({items: [1, 3, 5]})
+    expect(output).toEqual({items: [1, 4, 5]})
   })
 
   it('leaves input unchanged if no path expression matches', () => {

packages/core/src/document/patchOperations.ts

@@ -484,6 +484,9 @@ export function unset<R>(input: unknown, pathExpressions: string[]): R
 export function unset(input: unknown, pathExpressions: string[]): unknown {
   const result = pathExpressions
     .flatMap((pathExpression) => jsonMatch(input, pathExpression))
+    // ensure that we remove in the reverse order the paths were found in
+    // this is necessary for array unsets so the indexes don't change as we unset
+    .reverse()
     .reduce((acc, {path}) => unsetDeep(acc, path), input)
 
   return ensureArrayKeysDeep(result)