Swagger Codegen CLI swallows RuntimeException, always returns success (0) exit code.

Description

Swagger Codegen CLI is swallowing all RuntimeExceptions thrown throughout the tool, and returns a success exit status (0). This makes it impossible to determine if errors occurred on our CI jobs while generating code.

https://github.com/swagger-api/swagger-codegen/blob/master/modules/swagger-codegen/src/main/java/io/swagger/codegen/Codegen.java#L109-L120

Swagger-codegen version

3.0.20

current HEAD of 3.0.0 branch.

Swagger declaration file content or url

Any spec - simply use an invalid handlebar template to trigger a RuntimeException.

Command line used for generation

java -classpath <swagger jars> -l swift -i <my.yaml> -o <anywhere> -c <my-configuration.json>

Steps to reproduce

Simply use invalid handlebar template to trigger a RuntimeException, run the tool, and then run the following (zsh example)

echo $?

It will print 0 even though runtime exception occurred.

Related issues/PRs

The following appear to have same or similar root cause:

10434, 6832, 1140

Suggest a fix/enhancement

At these lines here, where swallowing Exception, simply add:

System.exit(<Error code, greater than 0, that identifies an error occurred>)

https://github.com/swagger-api/swagger-codegen/blob/master/modules/swagger-codegen/src/main/java/io/swagger/codegen/Codegen.java#L109-L120

Start at modules/swagger-codegen/src/main/java/io/swagger/codegen/Codegen.java, especially lines 109-120 where the RuntimeException is swallowed. Reproduce the failure with an invalid Handlebars template using the documented CLI command, then verify that echo $? reports a nonzero status when generation fails.