godoc: log node printing error

Invaluable when changing template files.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/5571044

src/cmd/godoc/godoc.go

@@ -378,7 +378,10 @@ func writeNode(w io.Writer, fset *token.FileSet, x interface{}) {
 	//           with an another printer mode (which is more efficiently
 	//           implemented in the printer than here with another layer)
 	mode := printer.TabIndent | printer.UseSpaces
-	(&printer.Config{mode, *tabwidth}).Fprint(&tconv{output: w}, fset, x)
+	err := (&printer.Config{mode, *tabwidth}).Fprint(&tconv{output: w}, fset, x)
+	if err != nil {
+		log.Print(err)
+	}
 }
 
 func filenameFunc(path string) string {