Check errors in many places

Admittedly, in some places just document the fact that we ignore error
return values, 'cause we don't know what to do with it.  At least, the
linter is happy.

handlers.go

@@ -159,7 +159,7 @@ func GetConfig(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	w.Write(bytes)
+	_, _ = w.Write(bytes)
 }
 
 // SaveConfig allows for a config to be saved.
@@ -272,7 +272,7 @@ func ListBlobs(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	w.Write(data)
+	_, _ = w.Write(data)
 }
 
 // CheckBlob tests whether a blob exists.
@@ -322,7 +322,11 @@ func GetBlob(w http.ResponseWriter, r *http.Request) {
 
 	wc := datacounter.NewResponseWriterCounter(w)
 	http.ServeContent(wc, r, "", time.Unix(0, 0), file)
-	file.Close()
+
+	if err = file.Close(); err != nil {
+		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+		return
+	}
 
 	if Config.Prometheus {
 		labels := prometheus.Labels{"repo": getRepo(r), "type": pat.Param(r, "type")}
@@ -354,8 +358,8 @@ func SaveBlob(w http.ResponseWriter, r *http.Request) {
 
 	written, err := io.Copy(tf, r.Body)
 	if err != nil {
-		tf.Close()
-		os.Remove(path)
+		_ = tf.Close()
+		_ = os.Remove(path)
 		if Config.Debug {
 			log.Print(err)
 		}
@@ -364,8 +368,8 @@ func SaveBlob(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := tf.Sync(); err != nil {
-		tf.Close()
-		os.Remove(path)
+		_ = tf.Close()
+		_ = os.Remove(path)
 		if Config.Debug {
 			log.Print(err)
 		}
@@ -374,7 +378,7 @@ func SaveBlob(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if err := tf.Close(); err != nil {
-		os.Remove(path)
+		_ = os.Remove(path)
 		if Config.Debug {
 			log.Print(err)
 		}