Application panics on ICA host keeper instantiation

[GAtom22]

Summary of Bug

When trying to upgrade the Evmos chain to use ibc-go v7.5.0, encountered an issue related to the changes introduced in #5785.

On starting the chain binary, the application panics with the error

panic: proto: could not resolve import "iavl/changeset.proto": not found

This panic is triggered in the newModuleQuerySafeAllowList function, when calling gogoproto.MergedRegistry(). It is related to the memIAVL dependency, specifically the memiavl/wal.proto file.

The panic happens because the file is registered using the proto.RegisterFile function which uses FileOptions{AllowUnresolvable: true}, while the gogoproto.MergedRegistry() uses the function protodesc.NewFiles(), which uses FileOptions{}.NewFiles(fd) (i.e. AllowUnresolvable: false). In the protodesc.New() function called by the protodesc.NewFiles() there's the corresponding logic

...
               if err == protoregistry.NotFound && (o.AllowUnresolvable || imp.IsWeak) {
			f = filedesc.PlaceholderFile(path)
		} else if err != nil {
			return nil, errors.New("could not resolve import %q: %v", path, err)
		}
...

In the reported case, the error is protoregistry.NotFound and the o.AllowUnresolvable == false, so the application panics.

Expected Behaviour

Should not panic

Version

v7.5.0

And any other version with the changes introduced in #5785

Steps to Reproduce

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For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged/assigned

[colin-axner]

For my understanding, essentially there are imports that could not be resolved by proto. By allowing these imports to be unresolved and thus replaced by a placeholder file, we avoid a panic and this is safe because the files in question are unused?