How can I handle incomplete paths efficiently? (products/ vs products/1)

I have a series of HTTP endpoints that involve lambda functions that hit detail end points like so:

products/1
users/1
package/998134

There is not a corresponding endpoint for products/, users/ or package/. I have a custom authorizer around the users/{id} and package/{id} endpoints.

If a user goes to users/ or packages/ using GET they receive {"message":"Missing Authentication Token"}. If they hit these end points with POST (a valid option for my endpoint if they were to also pass the ID) they receive

{'message': "Authorization header requires 'Credential' parameter. Authorization header requires 'Signature' parameter. Authorization header requires 'SignedHeaders' parameter. Authorization header requires existence of either a 'X-Amz-Date' or a 'Date' header. Authorization=MYTOKENHERE"}

Is there a way to adjust either of these messages? My first thought was to just create that associated end points:

GET users/
POST users/
GET products/
POST products/
GET package/
POST package

But that quickly gets to be a lot of work because I have more than three of these end points to do. I also need to include DELETE on a few of those.

Can I easily create a response for invalid or incomplete endpoints?

My serverless.yml has definitions that look like this currently:

show_user:
  handler: users/show_users.return_user
  events:
    - http:
        path: users/{id}
        method: get
        cors: true
update_user:
  handler: users/update_user.update_user
  events:
    - http:
        path: users/{id}
        method: post
        cors: true
        authorizer: ${self:custom.authorizer.users}

You can use method: any in place of configuring each method individually. Assuming they’re all returning the same error message then your configuration could be as simple as:

some_error:
  handler: somer_error.handler
  events:
    - http
        path: /users
        method: any
    - http
        path: /product
        method: any
    - http
        path: /package
        method: any