Suppose you have some buildspec.yml file like this that build your project and upload it on some where :

build:
     commands:
       - ng build --configuration=$BUILD_ENV  
post_build:
     commands:
       - aws s3 rm s3://$ENV_BUCKET  --recursive
       - aws s3 cp dist s3://$ENV_BUCKET  --recursive

the Problem here is that if build step fails codebuild continue and post_build will be executed and aws s3 rm will clean your bucket !

I had this issue in my aws codepipeline project (fortunately none-production env) and tried to fixing it.

So here is workaround:
on-failure: ABORT
just put in build step . i tried it and it works like a charm !

build:
     on-failure: ABORT
     commands:
       - ng build --configuration=$BUILD_ENV  
post_build:
     commands:
       - aws s3 rm s3://$ENV_BUCKET  --recursive
       - aws s3 cp dist s3://$ENV_BUCKET  --recursive

Second solution is to add another Deploy Stage in aws code pipeline and do deploy action (cp to s3 bucket ) at there .