Add DisplayError to show user errors from the backend

frontend/src/utilities/errors.ts

@@ -0,0 +1,36 @@
+import { createDialog, dismissDialog } from "@/utilities/dialog";
+import { TextButtonWidget } from "@/components/widgets/widgets";
+import { ResponseType, registerResponseHandler, Response, DisplayError } from "@/utilities/response-handler";
+
+export function comingSoon(issueNumber?: number) {
+	const bugMessage = `— but you can help add it!\nSee issue #${issueNumber} on GitHub.`;
+	const details = `This feature is not implemented yet${issueNumber ? bugMessage : ""}`;
+
+	const okButton: TextButtonWidget = {
+		kind: "TextButton",
+		callback: async () => dismissDialog(),
+		props: { label: "OK", emphasized: true, minWidth: 96 },
+	};
+	const issueButton: TextButtonWidget = {
+		kind: "TextButton",
+		callback: async () => window.open(`https://github.com/GraphiteEditor/Graphite/issues/${issueNumber}`, "_blank"),
+		props: { label: `Issue #${issueNumber}`, minWidth: 96 },
+	};
+	const buttons = [okButton];
+	if (issueNumber) buttons.push(issueButton);
+
+	createDialog("Warning", "Coming soon", details, buttons);
+}
+
+registerResponseHandler(ResponseType.DisplayError, (responseData: Response) => {
+	const data = responseData as DisplayError;
+
+	const okButton: TextButtonWidget = {
+		kind: "TextButton",
+		callback: async () => dismissDialog(),
+		props: { label: "OK", emphasized: true, minWidth: 96 },
+	};
+	const buttons = [okButton];
+
+	createDialog("Warning", "Editor error", data.description, buttons);
+});