fix(coding): preserve runtime model and failure contracts

electron/coding-runtime/runtime-errors.ts

@@ -0,0 +1,14 @@
+import type {
+  CodingRuntimeErrorCode,
+  CodingRuntimePublicError,
+} from './contracts';
+
+export class CodingRuntimeContractError extends Error {
+  readonly publicError: CodingRuntimePublicError;
+
+  constructor(code: CodingRuntimeErrorCode, message: string, recoverable: boolean) {
+    super(message);
+    this.name = 'CodingRuntimeContractError';
+    this.publicError = { code, message, recoverable };
+  }
+}