[MM-40682] - SIGSEGV after upgrade from 6.1.0 to 6.2.0 (#19192)

* [MM-40682] - SIGSEGV after upgrade from 6.1.0 to 6.2.0

* feedback impl

app/plugin.go

@@ -176,7 +176,9 @@ func (ch *Channels) initPlugins(c *request.Context, pluginDir, webappPluginDir s
 	ch.pluginsLock.RUnlock()
 	if pluginsEnvironment != nil || !*ch.srv.Config().PluginSettings.Enable {
 		ch.syncPluginsActiveState()
-		pluginsEnvironment.TogglePluginHealthCheckJob(*ch.srv.Config().PluginSettings.EnableHealthCheck)
+		if pluginsEnvironment != nil {
+			pluginsEnvironment.TogglePluginHealthCheckJob(*ch.srv.Config().PluginSettings.EnableHealthCheck)
+		}
 		return
 	}
 

app/plugin_test.go

@@ -20,6 +20,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	"github.com/mattermost/mattermost-server/v6/app/request"
 	"github.com/mattermost/mattermost-server/v6/model"
 	"github.com/mattermost/mattermost-server/v6/plugin"
 	"github.com/mattermost/mattermost-server/v6/shared/mlog"
@@ -628,6 +629,37 @@ func TestPluginSync(t *testing.T) {
 	}
 }
 
+// See https://github.com/mattermost/mattermost-server/issues/19189
+func TestChannelsPluginsInit(t *testing.T) {
+	th := Setup(t)
+	defer th.TearDown()
+
+	runNoPanicTest := func(t *testing.T) {
+		ctx := request.EmptyContext()
+		path, _ := fileutils.FindDir("tests")
+
+		require.NotPanics(t, func() {
+			th.Server.Channels().initPlugins(ctx, path, path)
+		})
+	}
+
+	t.Run("no panics when plugins enabled", func(t *testing.T) {
+		th.App.UpdateConfig(func(cfg *model.Config) {
+			*cfg.PluginSettings.Enable = true
+		})
+
+		runNoPanicTest(t)
+	})
+
+	t.Run("no panics when plugins disabled", func(t *testing.T) {
+		th.App.UpdateConfig(func(cfg *model.Config) {
+			*cfg.PluginSettings.Enable = false
+		})
+
+		runNoPanicTest(t)
+	})
+}
+
 func TestSyncPluginsActiveState(t *testing.T) {
 	th := Setup(t)
 	defer th.TearDown()