Fix endless loop with recursive types

[jmattheis]

Fixes #73

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.04 :tada:

Comparison is base (555ca5a) 96.94% compared to head (9c1cd5c) 96.98%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #74 +/- ## ========================================== + Coverage 96.94% 96.98% +0.04% ========================================== Files 25 25 Lines 1536 1561 +25 ========================================== + Hits 1489 1514 +25 Misses 29 29 Partials 18 18 ``` | [Impacted Files](https://codecov.io/gh/jmattheis/goverter/pull/74?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jannis+Mattheis) | Coverage Δ | | |---|---|---| | [builder/builder.go](https://codecov.io/gh/jmattheis/goverter/pull/74?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jannis+Mattheis#diff-YnVpbGRlci9idWlsZGVyLmdv) | `100.00% <100.00%> (ø)` | | | [generator/generator.go](https://codecov.io/gh/jmattheis/goverter/pull/74?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jannis+Mattheis#diff-Z2VuZXJhdG9yL2dlbmVyYXRvci5nbw==) | `95.27% <100.00%> (+0.27%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jannis+Mattheis). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jannis+Mattheis)

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