Remove `PerformError` (#3066)

This removes `PerformError`, which was needed when we still had
polylith.

This removes quite a bunch of
```go
if err != nil {
	return err
}
if err := res.Error; err != nil {
	return err.JSONResponse()
}
```

Hopefully can be read commit by commit. [skip ci]

1 files changed, 24 insertions, 4 deletions

diff --git a/federationapi/routing/invite.go b/federationapi/routing/invite.go
index a4ebeaed..6fa37f4a 100644
--- a/federationapi/routing/invite.go
+++ b/federationapi/routing/invite.go
@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"net/http"
 
+	"github.com/getsentry/sentry-go"
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 	"github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/dendrite/roomserver/types"
@@ -205,17 +206,36 @@ func processInvite(
 		SendAsServer:    string(api.DoNotSendToOtherServers),
 		TransactionID:   nil,
 	}
-	response := &api.PerformInviteResponse{}
-	if err := rsAPI.PerformInvite(ctx, request, response); err != nil {
+
+	if err = rsAPI.PerformInvite(ctx, request); err != nil {
 		util.GetLogger(ctx).WithError(err).Error("PerformInvite failed")
 		return util.JSONResponse{
 			Code: http.StatusInternalServerError,
 			JSON: jsonerror.InternalServerError(),
 		}
 	}
-	if response.Error != nil {
-		return response.Error.JSONResponse()
+
+	switch e := err.(type) {
+	case api.ErrInvalidID:
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.Unknown(e.Error()),
+		}
+	case api.ErrNotAllowed:
+		return util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden(e.Error()),
+		}
+	case nil:
+	default:
+		util.GetLogger(ctx).WithError(err).Error("PerformInvite failed")
+		sentry.CaptureException(err)
+		return util.JSONResponse{
+			Code: http.StatusInternalServerError,
+			JSON: jsonerror.InternalServerError(),
+		}
 	}
+
 	// Return the signed event to the originating server, it should then tell
 	// the other servers in the room that we have been invited.
 	if isInviteV2 {