errcheck issues fixed (#29061)

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

server/channels/app/plugin_health_check_test.go

@@ -78,7 +78,8 @@ func TestHealthCheckJob(t *testing.T) {
 	require.Equal(t, model.PluginStateFailedToStayRunning, env.GetPluginState(id))
 
 	// Activated manually, plugin should stay active
-	env.Activate(id)
+	_, _, err = env.Activate(id)
+	require.NoError(t, err)
 	job.CheckPlugin(id)
 	bundles = env.Active()
 	require.Equal(t, 1, len(bundles))