[builder] more information for missing gomod error

[kristinapathak]

Description

improving an error message - a missing gomod field would be reported but without informing where in the config the field is missing.

Link to tracking issue

Fixes #10474

Testing

Unit tests pass, added some tests for missing cases, manually tested

new error looks like:

../../bin/ocb_darwin_amd64 --config=./default.yaml
2024-06-27T11:39:10.316-0700	INFO	internal/command.go:125	OpenTelemetry Collector Builder	{"version": "", "date": "unknown"}
2024-06-27T11:39:10.319-0700	INFO	internal/command.go:161	Using config file	{"path": "./default.yaml"}
Error: invalid configuration: receiver module at index 0: missing gomod specification for module; provider module at index 2: missing gomod specification for module

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.33%. Comparing base (4a11a3e) to head (ea4a38a).

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10475   +/-   ##
=======================================
  Coverage   92.33%   92.33%           
=======================================
  Files         393      393           
  Lines       18647    18647           
=======================================
  Hits        17218    17218           
  Misses       1069     1069           
  Partials      360      360           

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[mx-psi]

Can we also add a test with an invalid but existing go.mod file?

[kristinapathak]

I can but that doesn't seem relevant to this PR? I'm wondering if this was confused for https://github.com/open-telemetry/opentelemetry-collector/pull/10098/files

[mx-psi]

Before the error said invalid gomod specification for module, so what I am wondering is if we are introducing a case where we say the go.mod file does not exist but what happens is that it's invalid. I am fine not adding the test on this PR if we are certain this does not happen

[kristinapathak]

The only validation being done currently is if the GoMod value is empty: if mod.GoMod == ""; here:
https://github.com/open-telemetry/opentelemetry-collector/pull/10475/files#diff-5aa5d2605e296c63681940c00cbc83eb2bb6b2e67ad2071f5c5c6435537d5561R240
There is no other validation of this config field. The field isn't a go.mod file, and it normally looks something like: go.opentelemetry.io/collector/confmap/provider/envprovider v0.103.0

[mx-psi]

Ah, thanks for clearing that up, that message sure was confusing to me 😄 we can merge this

[mx-psi]

Thanks, looks good to me!

[mx-psi]

Ah, thanks for clearing that up, that message sure was confusing to me 😄 we can merge this