From a5bb0cef09b32efdcf04a5584fd3933755355dbf Mon Sep 17 00:00:00 2001
From: "m.kindritskiy" <kindritskiy.m@gmail.com>
Date: Fri, 3 Apr 2026 16:08:29 +0300
Subject: [PATCH] Fix crash on malformed local mixin

---
 docs/docs/changelog.md           |  1 +
 internal/config/config/config.go |  2 +-
 internal/config/config/mixin.go  |  8 ++++++++
 internal/config/load_test.go     | 30 ++++++++++++++++++++++++++++++
 4 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/docs/docs/changelog.md b/docs/docs/changelog.md
index cfe8f42b..b7e84a97 100644
--- a/docs/docs/changelog.md
+++ b/docs/docs/changelog.md
@@ -23,6 +23,7 @@ title: Changelog
 * `[Fixed]` Resolve `go to definition` from command references such as `ref: build` to the referenced command in `lets self lsp`.
 * `[Added]` Load local mixin files into LSP storage and command index so mixin commands are available for navigation.
 * `[Changed]` Replace the top-level `--upgrade` flag with the `lets self upgrade` command.
+* `[Fixed]` Return a normal parse error when a local mixin contains malformed YAML instead of crashing.
 
 ## [0.0.59](https://github.com/lets-cli/lets/releases/tag/v0.0.59)
 
diff --git a/internal/config/config/config.go b/internal/config/config/config.go
index 3415e2bf..7070c2ce 100644
--- a/internal/config/config/config.go
+++ b/internal/config/config/config.go
@@ -292,7 +292,7 @@ func (c *Config) readMixins(mixins []*Mixin) error {
 
 	for _, mixin := range mixins {
 		if err := c.readMixin(mixin); err != nil {
-			return fmt.Errorf("failed to read remote mixin config '%s': %w", mixin.Remote.URL, err)
+			return fmt.Errorf("failed to read mixin config '%s': %w", mixin.Source(), err)
 		}
 	}
 
diff --git a/internal/config/config/mixin.go b/internal/config/config/mixin.go
index fd0bedd8..4b8b9c5f 100644
--- a/internal/config/config/mixin.go
+++ b/internal/config/config/mixin.go
@@ -190,3 +190,11 @@ func (m *Mixin) UnmarshalYAML(unmarshal func(any) error) error {
 func (m *Mixin) IsRemote() bool {
 	return m.Remote != nil
 }
+
+func (m *Mixin) Source() string {
+	if m.IsRemote() {
+		return m.Remote.URL
+	}
+
+	return m.FileName
+}
diff --git a/internal/config/load_test.go b/internal/config/load_test.go
index 7a0d62c6..3b92064e 100644
--- a/internal/config/load_test.go
+++ b/internal/config/load_test.go
@@ -1,6 +1,9 @@
 package config
 
 import (
+	"os"
+	"path/filepath"
+	"strings"
 	"testing"
 )
 
@@ -11,4 +14,31 @@ func TestLoadConfig(t *testing.T) {
 			t.Errorf("can not load test config: %s", err)
 		}
 	})
+
+	t.Run("returns error for malformed local mixin", func(t *testing.T) {
+		tempDir := t.TempDir()
+
+		mainConfig := "shell: bash\nmixins: [mixin.yaml]\ncommands:\n  ok:\n    cmd: echo ok\n"
+		if err := os.WriteFile(filepath.Join(tempDir, "lets.yaml"), []byte(mainConfig), 0o644); err != nil {
+			t.Fatalf("write main config: %v", err)
+		}
+
+		mixinConfig := "commands:\n  test1:\n    xxx\n    cmd: echo Test\n"
+		if err := os.WriteFile(filepath.Join(tempDir, "mixin.yaml"), []byte(mixinConfig), 0o644); err != nil {
+			t.Fatalf("write mixin config: %v", err)
+		}
+
+		_, err := Load("", tempDir, "0.0.0-test")
+		if err == nil {
+			t.Fatal("expected malformed mixin error")
+		}
+
+		if !strings.Contains(err.Error(), "failed to read mixin config 'mixin.yaml'") {
+			t.Fatalf("unexpected error: %v", err)
+		}
+
+		if !strings.Contains(err.Error(), "can not parse mixin config mixin.yaml") {
+			t.Fatalf("unexpected error: %v", err)
+		}
+	})
 }