Made the removal of non numeric values more robust.

nvidia_smi_exporter.go

@@ -45,6 +45,11 @@ func metrics(response http.ResponseWriter, request *http.Request) {
 		name := fmt.Sprintf("%s[%s]", row[0], row[1])
 		for idx, value := range row[2:] {
 			metric := strings.Replace(metricList[idx], ".", "_", -1)
+			// Non numerical values like [N/A] wil break prometeus when a number is expected.
+			_, err := strconv.Atoi(value)
+			if err != nil {
+				value = "-1"
+			}
 			result = fmt.Sprintf(
 				"%s%s{gpu=\"%s\"} %s\n", result,
 				metric, name, value)
@@ -54,7 +59,6 @@ func metrics(response http.ResponseWriter, request *http.Request) {
 		deviceCount, err = strconv.Atoi(max_id)
 		result = fmt.Sprintf(
 			"%sdeviceCount %d\n", result, deviceCount+1)
-		result = strings.Replace(result, "[Not Supported]", "-1", -1)
 
 	}