🚨 Add some tooling/ linting

errgroup.go

@@ -131,6 +131,12 @@ func (g *Group) TryGo(f func() error) bool {
 	return true
 }
 
+type ErrgroupLimitError struct{ Size int }
+
+func (egerr *ErrgroupLimitError) Error() string {
+	return fmt.Sprintf("errgroup: modify limit while %v goroutines in the group are still active", egerr.Size)
+}
+
 // SetLimit limits the number of active goroutines in this group to at most n.
 // A negative value indicates no limit.
 // A limit of zero will prevent any new goroutines from being added.
@@ -145,7 +151,8 @@ func (g *Group) SetLimit(n int) {
 		return
 	}
 	if len(g.sem) != 0 {
-		panic(fmt.Errorf("errgroup: modify limit while %v goroutines in the group are still active", len(g.sem)))
+		var err error = &ErrgroupLimitError{len(g.sem)}
+		panic(err)
 	}
 	g.sem = make(chan token, n)
 }