RangeError: Maximum call stack size exceeded

When I'm trying to upload [swagger.yaml](https://uecard-transport.korona.net/api/tcinformator/v1/regions/30/info/documents/swagger.yaml) to https://start.ktor.io/# I receive ```RangeError: Maximum call stack size exceeded```. Idea plugin in such case throwing an error without messages.

I deleted optional start begin of yaml document ```---``` and file has uploaded successfully to https://start.ktor.io/#.

You can simply reproduce that by adding optional start begin of yaml document ```---``` to ```ktor-init-tools/ktor-generator/src/jvmTest/resources/swagger.yaml``` and running ```ktor-init-tools/ktor-generator/src/jvmTest/kotlin/io/ktor/start/SwaggerGenerationTest.kt```

Reproduce the failure by adding the optional YAML document-start marker (`---`) to ktor-init-tools/ktor-generator/src/jvmTest/resources/swagger.yaml. Start with ktor-init-tools/ktor-generator/src/jvmTest/kotlin/io/ktor/start/SwaggerGenerationTest.kt and run it; done means the input no longer causes a maximum call stack error and the test passes.

Written by the indexing model from the issue text.