Unhandled error using multiple providers in stack configuration

[kylan11]

Describe the Bug

I am using a modified version of the "dns-delegated" component that does not require account-map, instead takes in two providers, as shown below:

dns-delegated:
      providers:
        aws:
          - region: eu-west-1
            alias: delegated
            assume_role: 
              role_arn: arn:aws:iam::1234567890:role/admin
          - region: eu-west-1
      metadata:
        component: aws/networking/dns-delegated
      vars:
        enabled: true

And as described here: https://atmos.tools/core-concepts/components/terraform/providers/

When running atmos, the following error occurs:

❯ atmos

 █████  ████████ ███    ███  ██████  ███████ 
██   ██    ██    ████  ████ ██    ██ ██      
███████    ██    ██ ████ ██ ██    ██ ███████ 
██   ██    ██    ██  ██  ██ ██    ██      ██ 
██   ██    ██    ██      ██  ██████  ███████ 
                                             

panic: reflect: call of reflect.Value.Index on map Value

goroutine 27 [running]:
reflect.Value.Index({0x2ab0600?, 0xc001a9d1a0?, 0xcc00d694698?}, 0x28da8e0?)
        /usr/lib/go/src/reflect/value.go:1432 +0x154
dario.cat/mergo.deepMerge({0x2ab0600?, 0xc000c9f518?, 0x2ab0600?}, {0x2ab0600?, 0xc001a9d2f0?, 0xc000dd05
f0?}, 0xc000dd06a0, 0x0, 0xc0013fb458)
        /home/kylan11/go/pkg/mod/dario.cat/[email protected]/merge.go:180 +0x2c6a
dario.cat/mergo.merge({0x2886180, 0xc000c9f518}, {0x2ab0600, 0xc001a9d2f0}, {0xc0003beb60, 0x3, 0x1?})
        /home/kylan11/go/pkg/mod/dario.cat/[email protected]/merge.go:395 +0x2d3
dario.cat/mergo.Merge(...)
        /home/kylan11/go/pkg/mod/dario.cat/[email protected]/merge.go:319
github.com/cloudposse/atmos/pkg/merge.MergeWithOptions({0xc000dd16a0, 0x4, 0xc000f44dc0?}, 0x0, 0x1)
        /home/kylan11/go/pkg/mod/github.com/cloudposse/[email protected]/pkg/merge/merge.go:68 +0x293
github.com/cloudposse/atmos/pkg/merge.Merge({{0xc0000581d0, 0x26}, {{{0xc000c921e0, 0x13}, 0x0, {0xc000c9
a9f0, 0x2f}, 0x1, 0x1, 0x1, ...}, ...}, ...}, ...)
        /home/kylan11/go/pkg/mod/github.com/cloudposse/[email protected]/pkg/merge/merge.go:105 +0x1ef
github.com/cloudposse/atmos/internal/exec.ProcessStackConfig({{0xc0000581d0, 0x26}, {{{0xc000c921e0, 0x13
}, 0x0, {0xc000c9a9f0, 0x2f}, 0x1, 0x1, 0x1, ...}, ...}, ...}, ...)
        /home/kylan11/go/pkg/mod/github.com/cloudposse/[email protected]/internal/exec/stack_processor_utils
.go:1008 +0x45d4
github.com/cloudposse/atmos/internal/exec.ProcessYAMLConfigFiles.func1(0x5, {0xc0009e36d0, 0x4d})
        /home/kylan11/go/pkg/mod/github.com/cloudposse/[email protected]/internal/exec/stack_processor_utils
.go:103 +0x7e5
created by github.com/cloudposse/atmos/internal/exec.ProcessYAMLConfigFiles in goroutine 1
        /home/kylan11/go/pkg/mod/github.com/cloudposse/[email protected]/internal/exec/stack_processor_utils
.go:58 +0x145

This stack's _defaults.yaml uses a single provider (not a list):

terraform:
  providers:
    aws:
      region: "eu-west-1"
      assume_role:
        role_arn: arn:aws:iam::1234567890:role/admin

list_merge_strategy is set to "merge".

There are multiple ways to fix, including:

• setting list_merge_strategy to replace or append (this results in a correctly handled error message)
• deleting one of the providers, making it an object
• making the _defaults.yaml provider a list of 1.

Expected Behavior

Atmos should either handle the use case of merging a single provider object to a list, or showing an handled error message.

Steps to Reproduce

Outlined in the bug description

Screenshots

No response

Environment

No response

Additional Context

No response

[aknysh]

@kylan11 thank you for reporting this.

This case was def not tested - define a map in the defaults, and a list in the other manifests.

for now, the best way for you to move forward would be "making the _defaults.yaml provider a list of 1.".

We are going to review and improve this in the next Atmos releases.