fix(core): Silently fail maybeInstrument

.size-limit.js

@@ -224,7 +224,7 @@ module.exports = [
     import: createImport('init'),
     ignore: ['next/router', 'next/constants'],
     gzip: true,
-    limit: '39.1 KB',
+    limit: '40 KB',
   },
   // SvelteKit SDK (ESM)
   {

packages/utils/src/instrument/handlers.ts

@@ -37,8 +37,12 @@ export function resetInstrumentationHandlers(): void {
 /** Maybe run an instrumentation function, unless it was already called. */
 export function maybeInstrument(type: InstrumentHandlerType, instrumentFn: () => void): void {
   if (!instrumented[type]) {
-    instrumentFn();
     instrumented[type] = true;
+    try {
+      instrumentFn();
+    } catch (e) {
+      DEBUG_BUILD && logger.error(`Error while instrumenting ${type}`, e);
+    }
   }
 }
 

packages/utils/test/instrument.test.ts

@@ -0,0 +1,13 @@
+import { maybeInstrument } from '../src';
+
+describe('maybeInstrument', () => {
+  test('does not throw when instrumenting fails', () => {
+    maybeInstrument('xhr', () => {
+      throw new Error('test');
+    });
+  });
+
+  test('does not throw when instrumenting fn is not a function', () => {
+    maybeInstrument('xhr', undefined as any);
+  });
+});