test(boot): cover the projection removal edge cases

A profile with the legacy directory but no node_modules, and a symlink whose target parent is gone, exercise the remaining branches of removeLinkProjections; the non-ENOENT realpath failure is a host filesystem fault and is excluded from coverage like its siblings.

packages/boot/app-boot/src/profile.ts

@@ -240,7 +240,9 @@ function pointsInto(link: string, root: string): boolean {
     return parent === rootPath || parent.startsWith(rootPath + sep)
   } catch (error) {
     // A target whose parent no longer exists cannot be one of the projections this launch owns.
+    /* v8 ignore next 2 -- a non-ENOENT realpath failure requires a host filesystem fault */
     if ((error as NodeJS.ErrnoException).code === 'ENOENT') return false
+    /* v8 ignore next -- see the host-filesystem exception above */
     throw error
   }
 }

packages/boot/app-boot/tests/profile.spec.ts

@@ -712,6 +712,21 @@ describe('removeLinkProjections', () => {
     expect(() => { removeLinkProjections(profile) }).not.toThrow()
   })
 
+  it('removes the directory when the profile has no node_modules and keeps links whose target parent is gone', () => {
+    const home = tmp()
+    const profile = join(home, 'profiles', 'web')
+    mkdirSync(join(profile, '.dsh-module-fallback', 'node_modules'), { recursive: true })
+    removeLinkProjections(profile)
+    expect(existsSync(join(profile, '.dsh-module-fallback'))).toBe(false)
+
+    const other = join(home, 'profiles', 'other')
+    mkdirSync(join(other, '.dsh-module-fallback', 'node_modules'), { recursive: true })
+    link(join(home, 'missing-parent', 'pkg'), join(other, 'node_modules', 'orphan'))
+    removeLinkProjections(other)
+    expect(existsSync(join(other, '.dsh-module-fallback'))).toBe(false)
+    expect(lstatSync(join(other, 'node_modules', 'orphan')).isSymbolicLink()).toBe(true)
+  })
+
   it('leaves a profile without the directory untouched', () => {
     const home = tmp()
     const profile = join(home, 'profiles', 'web')