fix: install exiting with 1 exit code and no error message (#9567)

close #9559

.changeset/empty-files-laugh.md

@@ -0,0 +1,6 @@
+---
+"@pnpm/core": patch
+"pnpm": patch
+---
+
+Installation should not exit with an error if `strictPeerDependencies` is `true` but all issues are ignored by `peerDependencyRules` [#9505](https://github.com/pnpm/pnpm/pull/9505).

cli/default-reporter/src/reportError.ts

@@ -444,7 +444,12 @@ function reportPeerDependencyIssuesError (
   strictPeerDependencies: false
 `)
   const rendered = renderPeerIssues(msg.issuesByProjects)
-  if (!rendered) return null
+  if (!rendered) {
+    // This should never happen.
+    return {
+      title: err.message,
+    }
+  }
   return {
     title: err.message,
     body: `${rendered}

pkg-manager/core/src/install/reportPeerDependencyIssues.ts

@@ -45,7 +45,7 @@ export function filterPeerDependencyIssues (
     newPeerDependencyIssuesByProjects[projectId] = { bad: {}, missing: {}, conflicts, intersections }
     for (const [peerName, issues] of Object.entries(missing)) {
       if (
-        ignoreMissingMatcher(peerName)
+        ignoreMissingMatcher(peerName) || issues.every(({ optional }) => optional)
       ) {
         continue
       }

pkg-manager/core/test/filterPeerDependencyIssues.test.ts

@@ -207,3 +207,36 @@ test('filterPeerDependencyIssues() allowed versions', () => {
     },
   })
 })
+
+test('filterPeerDependencyIssues() ignores missing optional dependency issues', () => {
+  expect(filterPeerDependencyIssues({
+    '.': {
+      missing: {
+        aaa: [
+          {
+            parents: [
+              {
+                name: 'xxx',
+                version: '1.0.0',
+              }],
+
+            optional: true,
+            wantedRange: '>=1.0.0 <3.0.0',
+          },
+        ],
+      },
+      bad: {},
+      conflicts: [],
+      intersections: {},
+    },
+  }, {
+    allowAny: [],
+  })).toStrictEqual({
+    '.': {
+      bad: {},
+      conflicts: [],
+      intersections: {},
+      missing: {},
+    },
+  })
+})