Module mapping error message needs to be more actionable.

[bcsgh]

Description of the feature request:

I made some changes and got an error message like this:

ERROR: Error computing the main repository mapping: module not found in registries: [email protected]

While this tells me that something is wrong, it gives almost no information about what went wrong or how to fix it. In my case, the module and version existed in one of the registries provided via --registry= but Bazel provided no information about why it wasn't found or even where it was looked for.

What I would like to see is that message followed by an ordered enumeration of everywhere Bazel could possibly get the module from and either what it found or why it didn't look:

ERROR: Error computing the main repository mapping: module not found in registries: [email protected]
https://bcr.bazel.build (from --registry): not found (from MODULE.bazel.lock)
https://bcsgh.github.io/bazel-registry (from --registry): not found (from MODULE.bazel.lock)
file:///home/bcs/bazel-registry-private/ (from --registry): not found (from file://)

Eventually I figured out that deleting MODULE.bazel.lock fixed the problem, but that was just a lucky guess. The (from MODULE.bazel.lock) would have been the important part in my case.

A flag to get even more details (like full URLs inspected) would be useful as well.

Which category does this issue belong to?

Core

What underlying problem are you trying to solve with this feature?

UX/Usability

Which operating system are you running Bazel on?

n/a

What is the output of bazel info release?

release 8.0.0

If bazel info release returns development version or (@non-git), tell us how you built Bazel.

No response

What's the output of git remote get-url origin; git rev-parse HEAD ?

Not public

Have you found anything relevant by searching the web?

No response

Any other information, logs, or outputs that you want to share?

No response