[BUG] Null Reference Exception when using --model-name-suffix for fsharp-giraffe-server generator

When running this commande openapi-generator generate -i api.yml -g fsharp-giraffe-server --dry-run --model-name-suffix "Dto" I get the following exception:

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.util.Map.put(Object, Object)" because "models" is null
        at org.openapitools.codegen.DefaultGenerator.generateModels(DefaultGenerator.java:512)
        at org.openapitools.codegen.DefaultGenerator.generate(DefaultGenerator.java:875)
        at org.openapitools.codegen.cmd.Generate.execute(Generate.java:441)
        at org.openapitools.codegen.cmd.OpenApiGeneratorCommand.run(OpenApiGeneratorCommand.java:32)
        at org.openapitools.codegen.OpenAPIGenerator.main(OpenAPIGenerator.java:66)

When I run it with any other generator, I don't get the exception:
openapi-generator generate -i api.yml -g aspnetcore --dry-run --model-name-suffix "Dto"

When I run it without --model-name-suffix, I don't get the exception:
openapi-generator generate -i api.yml -g fsharp-giraffe-server --dry-run

@nmfisher Could it be that this option is not supported yet for the F# generator?

Reproduce the command with the fsharp-giraffe-server generator and --model-name-suffix, then trace the failure from org.openapitools.codegen.DefaultGenerator.generateModels at line 512 through the generator configuration. Compare this path with the aspnetcore run and the no-suffix run. Done means the F# generator no longer raises the NullPointerException, or its unsupported-option behavior is explicitly established.