fix(sveltekit): Keep source maps of the hooks files under a base path

Author: logaretm

packages/sveltekit/src/vite/tunnelBasePath.ts

@@ -1,4 +1,5 @@
 import { escapeStringForRegex } from '@sentry/core';
+import MagicString from 'magic-string';
 import type { Plugin } from 'vite';
 import { TUNNEL_BASE_PATH_GLOBAL } from '../common/tunnel';
 import type { ResolvedKitConfig } from './kitConfig';
@@ -40,7 +41,10 @@ export function makeTunnelBasePathPlugin(getKitConfig: () => Promise<ResolvedKit
         return null;
       }
 
-      return { code: `import ${JSON.stringify(VIRTUAL_BASE_PATH_FILE)};\n${code}`, map: null };
+      const ms = new MagicString(code);
+      ms.prepend(`import ${JSON.stringify(VIRTUAL_BASE_PATH_FILE)};\n`);
+
+      return { code: ms.toString(), map: ms.generateMap({ hires: true }) };
     },
   };
 }

packages/sveltekit/test/vite/tunnelBasePath.test.ts

@@ -20,7 +20,7 @@ describe('makeTunnelBasePathPlugin', () => {
     for (const id of ['/p/src/hooks.server.ts', '/p/src/hooks.client.js', '/p/src/instrumentation.server.ts']) {
       expect(transform('const a = 1;', id)).toEqual({
         code: `import ${JSON.stringify('\0sentry-sveltekit-tunnel-base-path')};\nconst a = 1;`,
-        map: null,
+        map: expect.objectContaining({ mappings: expect.any(String) }),
       });
     }
     expect(transform('const a = 1;', '/p/src/routes/+page.svelte')).toBeNull();