feat(sveltekit): Add wrapper for remote function invocation

packages/sveltekit/src/server-common/remoteFunctions.ts

@@ -0,0 +1,41 @@
+import { addNonEnumerableProperty, captureException, flushIfServerless, startSpan } from '@sentry/core';
+import type { LoadEvent } from '@sveltejs/kit';
+import type { SentryWrappedFlag } from '../common/utils';
+
+type PatchedRequestEvent = LoadEvent & SentryWrappedFlag;
+
+/**
+ * Wraps a remote function invokation with a Sentry span and captures an exception if the remote function throws.
+ */
+export function wrapRemoteFunctionWithSentry<T extends (...args: any) => any>(origRemoteFn: T): T {
+  return new Proxy(origRemoteFn, {
+    apply: async (wrappingTarget, thisArg, args: Parameters<T>) => {
+      // Type casting here because `T` cannot extend `Load` (see comment above function signature)
+      // Also, this event possibly already has a sentry wrapped flag attached
+      const event = args[0] as PatchedRequestEvent;
+
+      if (event.__sentry_wrapped__) {
+        return wrappingTarget.apply(thisArg, args);
+      }
+
+      addNonEnumerableProperty(event as unknown as Record<string, unknown>, '__sentry_wrapped__', true);
+
+      const routeId = event.route?.id;
+
+      try {
+        // We need to await before returning, otherwise we won't catch any errors thrown by the load function
+        return await startSpan(
+          {
+            name: routeId ? routeId : event.url.pathname,
+          },
+          () => wrappingTarget.apply(thisArg, args),
+        );
+      } catch (e) {
+        captureException(e);
+        throw e;
+      } finally {
+        await flushIfServerless();
+      }
+    },
+  });
+}