fix(store): forFeature using instanceof instead of typeof

[timdeschryver]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngrx/platform/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Closes #2919

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

The local build of this PR, works on the reprodution repo

[brandonroberts]

I wonder why this didn't fail when we build the libraries 🤔

[bbortt]

just checked it out and it does indeed fix my issue - you guys are awesome 🚀

[timdeschryver]

I have no idea why... I even tried with the upgrade to v11.2, but the behavior was the same.