feat(tsbundle): add configurable maxLineLength for base64ts output and improve build/error handling in child builds

ts/tsbundle.class.tsbundle.ts

@@ -45,7 +45,11 @@ export class TsBundle {
     );
     const childProcess = await threadsimple.start();
     childProcess.on('exit', (status) => {
-      done.resolve();
+      if (status !== 0) {
+        done.reject(new Error(`Bundle build failed with exit code ${status}`));
+      } else {
+        done.resolve();
+      }
     });
     await done.promise;
   }