segfault when using the return of a path which combines IndexAll and Child

[cezarguimaraes]

Describe the bug
Attempting to use the filtered value (i.e node.String() or ast.Walk) of a path which combines IndexAll and Child might lead to seg fault if not all sequence elements contain the property being selected by Child

To Reproduce

https://go.dev/play/p/hxD0l_fdVYO

I have added a test case here that reproduces the issue

cezarguimaraes@19b7508

Expected behavior

Taking jq as inspiration, partial results should be returned, possibly with nil elements:

$ echo '[{"foo": 1}, {}]' | jq ".[].foo"
1
null

Screenshots

Version Variables

• Go version: go version go1.22.1 linux/amd64
• go-yaml's Version: (tag: v1.11.3) and main

Additional context
I have a tentative fix in this branch master...cezarguimaraes:go-yaml:fix-indexAll-child-segfault
As can be seen by the tests added, the code from this branch simulates jq behavior by returning ast.Null. Another possible approach (preserved by the comments in (*indexAllNode).filter completely filter out unmatched nodes.