[JAVASCRIPT] NodeJS undefined result when calling endpoints that return blob

Description

When generating a Javascript client for an API that returns a byte stream, the client is documented to receive a "Blob" type. In ApiClient.js's deserialize method, there is a check to see if response.body is either null or an object with no keys, and if so, response.text will be returned as-is. It turns out that response.body is an empty object when running under NodeJS. This causes the logic to use response.text which is undefined, because the incoming stream should be read from response.res, which is not handled at all by the deserialize method.

Swagger-codegen version

2.4.0, not a regression.

Swagger declaration file content or url

{
"responses": {
"200": {
"description": "successful operation",
"schema": {
"type": "array",
"items": {
"type": "string",
"format": "byte"
}
}
}
}
}

Command line used for generation

config:

{
    "usePromises": true,
    "useES6": false
}

command-line:

$SWAGGER_CODEGEN generate \
        -l javascript \
        -i $SWAGGER_URL \
        -c js-config.json \
        -o $OUTPUT_DIR

Steps to reproduce

Call the client code as normal. It actually makes a successful request to the remote endpoint, but it returns a Promise that resolves to undefined.

Related issues/PRs

This one is similar but not completely related:
https://github.com/swagger-api/swagger-codegen/issues/3297

Suggest a fix/enhancement

For NodeJS, it would be possible to check if response.res is a readable stream, and use it. I don't know how this will affect browsers though.

Start in the generated JavaScript client's ApiClient.js and inspect the deserialize method, especially its handling of response.body, response.text, and response.res. Reproduce the byte-stream endpoint case under NodeJS and verify that the returned Promise resolves to the response data rather than undefined, while checking the browser behavior described in the issue.