Add default status code for lambra integration http event

examples/babel/serverless.yml

@@ -15,3 +15,4 @@ functions:
       - http:
           method: get
           path: hello
+          integration: lambda

examples/include-external-npm-packages/serverless.yml

@@ -18,3 +18,4 @@ functions:
       - http:
           method: GET
           path: first
+          integration: lambda

examples/multiple-entries/serverless.yml

@@ -21,3 +21,4 @@ functions:
       - http:
           method: GET
           path: second
+          integration: lambda

examples/typescript/serverless.yml

@@ -15,3 +15,4 @@ functions:
       - http:
           method: get
           path: hello
+          integration: lambda

lib/serve.js

@@ -122,7 +122,7 @@ module.exports = {
         }
 
         if (isLambdaProxyIntegration) {
-          res.status(resp.statusCode).send(resp.body);
+          res.status(resp.statusCode || 200).send(resp.body);
         } else {
           res.status(200).send(resp);
         }