internal/postgres: include less in error message

The error messages from UpsertModuleVersionState included a large data structure.
Just include the module path and version.

Change-Id: I1e68f387c7cf2f3aacf959b443e738e6852fb02d
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/304929
Trust: Jonathan Amsterdam <jba@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Julie Qiu <julie@golang.org>
diff --git a/internal/postgres/versionstate.go b/internal/postgres/versionstate.go
index a98f695..7ed3d5d 100644
--- a/internal/postgres/versionstate.go
+++ b/internal/postgres/versionstate.go
@@ -56,7 +56,7 @@
 // UpsertModuleVersionState inserts or updates the module_version_state table with
 // the results of a fetch operation for a given module version.
 func (db *DB) UpsertModuleVersionState(ctx context.Context, mvs *ModuleVersionStateForUpsert) (err error) {
-	defer derrors.WrapStack(&err, "UpsertModuleVersionState(ctx, %+v", mvs)
+	defer derrors.WrapStack(&err, "UpsertModuleVersionState(ctx, %s@%s)", mvs.ModulePath, mvs.Version)
 	ctx, span := trace.StartSpan(ctx, "UpsertModuleVersionState")
 	defer span.End()