Master branch seem broken... CodegenConfiguratorTest.testFromFile:268 expected [1] but found [0]

[allComputableThings]

Came to make the dart extensions work with code that requires null safety (standard for some years now).

Found that master is broken.

 8298  git clone https://github.com/swagger-api/swagger-codegen
 8299  cd swagger-codegen
 8300  ./run-in-docker.sh mvn package

[INFO] 
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running TestSuite
[main] INFO io.swagger.parser.Swagger20Parser - reading from src/test/resources/1_2/petstore-1.2/api-docs
[main] INFO io.swagger.parser.Swagger20Parser - reading from src/test/resources/1_2/petstore-1.2/api-docs
[main] INFO io.swagger.parser.Swagger20Parser - reading from src/test/resources/2_0/petstore-with-fake-endpoints-models-for-testing.yaml
[main] INFO io.swagger.parser.Swagger20Parser - reading from src/test/resources/2_0/petstore-with-fake-endpoints-models-for-testing.yaml
[main] INFO io.swagger.codegen.languages.JavascriptClientCodegen - Using JS ES5 templates
[main] INFO io.swagger.codegen.languages.JavascriptClientCodegen - Using JS ES5 templates
[main] INFO io.swagger.parser.Swagger20Parser - reading from src/test/resources/2_0/recursive_model.yaml
[main] INFO io.swagger.codegen.ignore.CodegenIgnoreProcessor - No .swagger-codegen-ignore file found.
[main] INFO io.swagger.codegen.languages.JavascriptClientCodegen - Using JS ES5 templates
[main] ERROR io.swagger.codegen.DefaultCodegen - String to be sanitized is null. Default to Object

[INFO] 
[INFO] Results:
[INFO] 
[ERROR] Failures: 
[ERROR]   CodegenConfiguratorTest.testFromFile:268 expected [1] but found [0]
```