fix: skip export conditions without a source

Author: stipsan

src/node/core/pkg/parseExports.ts

@@ -174,7 +174,7 @@ export function parseExports(options: {
       }
     } else if (isRecord(exportEntry) && 'svelte' in exportEntry) {
       // @TODO should we report a warning or a debug message here about a detected svelte export that is ignored?
-    } else if (isRecord(exportEntry)) {
+    } else if (isPkgExport(exportEntry)) {
       const exp = {
         _exported: true,
         _path: exportPath,
@@ -240,7 +240,7 @@ export function parseExports(options: {
       }
 
       _exports.push(exp)
-    } else {
+    } else if (!isRecord(exportEntry)) {
       errors.push('package.json: exports must be an object')
     }
   }
@@ -253,3 +253,7 @@ export function parseExports(options: {
 
   return _exports
 }
+
+function isPkgExport(value: unknown): value is PkgExport {
+  return isRecord(value) && 'source' in value && typeof value['source'] === 'string'
+}

src/node/core/pkg/types.ts

@@ -15,7 +15,7 @@ export interface PackageJSON {
     string,
     | `./${string}.json`
     | {
-        source: string
+        source?: string
         types?: string
         browser?: {
           source: string