chore: create interface for pkgs to return codersdk errors (#18719)

This interface allows it to create rich codersdk errors and pass them up to the `wsbuilder` error handling.

coderd/wsbuilder/wsbuilder.go

@@ -240,6 +240,9 @@ type BuildError struct {
 }
 
 func (e BuildError) Error() string {
+	if e.Wrapped == nil {
+		return e.Message
+	}
 	return e.Wrapped.Error()
 }
 
@@ -247,6 +250,13 @@ func (e BuildError) Unwrap() error {
 	return e.Wrapped
 }
 
+func (e BuildError) Response() (int, codersdk.Response) {
+	return e.Status, codersdk.Response{
+		Message: e.Message,
+		Detail:  e.Error(),
+	}
+}
+
 // Build computes and inserts a new workspace build into the database.  If authFunc is provided, it also performs
 // authorization preflight checks.
 func (b *Builder) Build(

coderd/wsbuilder/wsbuilder_test.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/coder/coder/v2/coderd/coderdtest"
 	"github.com/coder/coder/v2/coderd/files"
+	"github.com/coder/coder/v2/coderd/httpapi/httperror"
 	"github.com/coder/coder/v2/provisionersdk"
 
 	"github.com/google/uuid"
@@ -1000,6 +1001,23 @@ func TestWorkspaceBuildDeleteOrphan(t *testing.T) {
 	})
 }
 
+func TestWsbuildError(t *testing.T) {
+	t.Parallel()
+
+	const msg = "test error"
+	var buildErr error = wsbuilder.BuildError{
+		Status:  http.StatusBadRequest,
+		Message: msg,
+	}
+
+	respErr, ok := httperror.IsResponder(buildErr)
+	require.True(t, ok, "should be a Coder SDK error")
+
+	code, resp := respErr.Response()
+	require.Equal(t, http.StatusBadRequest, code)
+	require.Equal(t, msg, resp.Message)
+}
+
 type txExpect func(mTx *dbmock.MockStore)
 
 func expectDB(t *testing.T, opts ...txExpect) *dbmock.MockStore {