cli: fix typesVersions generation in prepack

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/kind-waves-impress.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Fixed the package prepack command so that it no longer produces unnecessary `index` entries in the `typesVersions` map, which could cause `/index` to be added when automatically adding imports.

packages/cli/src/modules/build/lib/packager/productionPack.ts

@@ -143,7 +143,7 @@ async function rewriteEntryPoints(
 
   // Clear to ensure a clean slate before adding entries back in further down
   if (pkg.typesVersions) {
-    pkg.typesVersions = { '*': {} };
+    pkg.typesVersions = undefined;
   }
 
   for (const entryPoint of entryPoints) {
@@ -166,9 +166,8 @@ async function rewriteEntryPoints(
       if (!pkg.typesVersions) {
         pkg.typesVersions = { '*': {} };
       }
-      pkg.typesVersions['*'][entryPoint.name] = [
-        `dist/${entryPoint.name}.d.ts`,
-      ];
+      const mount = entryPoint.name === 'index' ? '*' : entryPoint.name;
+      pkg.typesVersions['*'][mount] = [`dist/${entryPoint.name}.d.ts`];
     }
 
     exp.default = exp.require ?? exp.import;
@@ -218,6 +217,14 @@ async function rewriteEntryPoints(
     }
   }
 
+  // Clean up the typesVersions field if it only contains a wildcard
+  if (pkg.typesVersions?.['*']) {
+    const keys = Object.keys(pkg.typesVersions['*']);
+    if (keys.length === 1 && keys[0] === '*') {
+      delete pkg.typesVersions;
+    }
+  }
+
   if (pkg.exports) {
     pkg.exports = outputExports;
     // We treat package.json as a fixed export that is always available in the published package