Hook provider.environment process

I want to work with object formatted data in my app environment. Currently my configuration causes me this error:

 Serverless Error ----------------------------------------

  Could not resolve "TABLES_TO_COPY" environment variable: Unsupported environment variable format: [
      sourceConnectionName: 'db_connection_main,
      sourceTable: 'users',
      targetConnectionName: 'db_connection_main_research',
      targetTable: 'users'

What I’d like to do is create a plugin that hooks the process of establishing provider.environment, so that I can stringify non-string properties like this. However, I can’t seem to find anything to hook to here. Where can I hook this?