ui: add PGCode to admin api errors

Adding the Error Code makes it easy to identify
the underlying issue of why the request failed.

old error:
```RequestError: An internal server error has occurred.
Please check your CockroachDB logs for more details.```

new error
```RequestError: An internal server error has occurred.
Please check your CockroachDB logs for more details. Error Code: 53200```

Epic: none
Closes: #98596

Release note: none

pkg/server/BUILD.bazel

@@ -219,6 +219,7 @@ go_library(
         "//pkg/sql/optionalnodeliveness",
         "//pkg/sql/parser",
         "//pkg/sql/pgwire",
+        "//pkg/sql/pgwire/pgcode",
         "//pkg/sql/pgwire/pgerror",
         "//pkg/sql/pgwire/pgwirecancel",
         "//pkg/sql/physicalplan",
@@ -482,6 +483,8 @@ go_test(
         "//pkg/sql/clusterunique",
         "//pkg/sql/execinfrapb",
         "//pkg/sql/idxusage",
+        "//pkg/sql/pgwire/pgcode",
+        "//pkg/sql/pgwire/pgerror",
         "//pkg/sql/roleoption",
         "//pkg/sql/sem/catconstants",
         "//pkg/sql/sem/tree",

pkg/server/admin.go

@@ -51,6 +51,8 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/isql"
 	"github.com/cockroachdb/cockroach/pkg/sql/optionalnodeliveness"
 	"github.com/cockroachdb/cockroach/pkg/sql/parser"
+	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgcode"
+	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
 	"github.com/cockroachdb/cockroach/pkg/sql/privilege"
 	"github.com/cockroachdb/cockroach/pkg/sql/roleoption"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
@@ -109,10 +111,6 @@ func nonTableDescriptorRangeCount() int64 {
 	}))
 }
 
-// apiServerMessage is the standard body for all HTTP 500 responses.
-var errAdminAPIError = grpcstatus.Errorf(codes.Internal, "An internal server error "+
-	"has occurred. Please check your CockroachDB logs for more details.")
-
 // A adminServer provides a RESTful HTTP API to administration of
 // the cockroach cluster.
 type adminServer struct {
@@ -309,14 +307,30 @@ func (s *adminServer) RegisterGateway(
 // the RPC endpoint method.
 func serverError(ctx context.Context, err error) error {
 	log.ErrorfDepth(ctx, 1, "%+v", err)
-	return errAdminAPIError
+
+	// Include the PGCode in the message for easier troubleshooting
+	errCode := pgerror.GetPGCode(err).String()
+	if errCode != pgcode.Uncategorized.String() {
+		errMessage := fmt.Sprintf("%s Error Code: %s", errAPIInternalErrorString, errCode)
+		return grpcstatus.Errorf(codes.Internal, errMessage)
+	}
+
+	// The error is already grpcstatus formatted error.
+	// Likely calling serverError multiple times on same error.
+	grpcCode := grpcstatus.Code(err)
+	if grpcCode != codes.Unknown {
+		return err
+	}
+
+	// Fallback to generic message
+	return errAPIInternalError
 }
 
 // serverErrorf logs the provided error and returns an error that should be returned by
 // the RPC endpoint method.
 func serverErrorf(ctx context.Context, format string, args ...interface{}) error {
 	log.ErrorfDepth(ctx, 1, format, args...)
-	return errAdminAPIError
+	return errAPIInternalError
 }
 
 // isNotFoundError returns true if err is a table/database not found error.

pkg/server/admin_test.go

@@ -47,6 +47,8 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descpb"
 	"github.com/cockroachdb/cockroach/pkg/sql/idxusage"
+	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgcode"
+	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/catconstants"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
 	"github.com/cockroachdb/cockroach/pkg/sql/sessiondatapb"
@@ -3249,6 +3251,22 @@ func TestAdminPrivilegeChecker(t *testing.T) {
 	}
 }
 
+func TestServerError(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	defer log.Scope(t).Close(t)
+	ctx := context.Background()
+	pgError := pgerror.New(pgcode.OutOfMemory, "TestServerError.OutOfMemory")
+	err := serverError(ctx, pgError)
+	require.Equal(t, "rpc error: code = Internal desc = An internal server error has occurred. Please check your CockroachDB logs for more details. Error Code: 53200", err.Error())
+
+	err = serverError(ctx, err)
+	require.Equal(t, "rpc error: code = Internal desc = An internal server error has occurred. Please check your CockroachDB logs for more details. Error Code: 53200", err.Error())
+
+	err = fmt.Errorf("random error that is not pgerror or grpcstatus")
+	err = serverError(ctx, err)
+	require.Equal(t, "rpc error: code = Internal desc = An internal server error has occurred. Please check your CockroachDB logs for more details.", err.Error())
+}
+
 func TestDatabaseAndTableIndexRecommendations(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	defer log.Scope(t).Close(t)