Convert to not nullable

lib/data/model/cpu_2_status.dart

@@ -6,9 +6,10 @@ class Cpu2Status {
   Cpu2Status(this.pre, this.now);
 
   double usedPercent({int coreIdx = 0}) {
-    final used = (now[coreIdx].idle - pre[coreIdx].idle) /
-        (now[coreIdx].total - pre[coreIdx].total);
-    return used.isNaN ? 0 : used;
+    final idleDelta = now[coreIdx].idle - pre[coreIdx].idle;
+    final totalDelta = now[coreIdx].total - pre[coreIdx].total;
+    final used = idleDelta / totalDelta;
+    return used.isNaN ? 0 : 100 - used * 100;
   }
 
   Cpu2Status update(List<CpuStatus> newStatus) {

lib/data/model/server_status.dart

@@ -28,18 +28,18 @@ class ServerStatus {
 } 
 */
 
-  Cpu2Status? cpu2Status;
-  List<int?>? memList;
-  String? sysVer;
-  String? uptime;
-  List<DiskInfo?>? disk;
-  TcpStatus? tcp;
+  late Cpu2Status cpu2Status;
+  late List<int?> memList;
+  late String sysVer;
+  late String uptime;
+  late List<DiskInfo?> disk;
+  late TcpStatus tcp;
 
   ServerStatus(
-      {this.cpu2Status,
+      this.cpu2Status,
       this.memList,
       this.sysVer,
       this.uptime,
       this.disk,
-      this.tcp});
+      this.tcp);
 }

lib/data/provider/server.dart

@@ -28,9 +28,11 @@ class ServerProvider extends BusyProvider {
       Cpu2Status([emptyCpuStatus], [emptyCpuStatus]);
 
   ServerStatus get emptyStatus => ServerStatus(
-      cpu2Status: emptyCpu2Status,
-      memList: [100, 0],
-      disk: [
+      emptyCpu2Status,
+      [100, 0],
+      '',
+      '',
+      [
         DiskInfo(
             mountLocation: '/',
             mountPath: '/',
@@ -39,9 +41,7 @@ class ServerProvider extends BusyProvider {
             avail: '0',
             usedPercent: 0)
       ],
-      sysVer: '',
-      uptime: '',
-      tcp: TcpStatus(maxConn: 0, active: 0, passive: 0, fail: 0));
+      TcpStatus(maxConn: 0, active: 0, passive: 0, fail: 0));
 
   Future<void> loadLocalData() async {
     setBusyState(true);
@@ -145,12 +145,12 @@ class ServerProvider extends BusyProvider {
     final tcp = await client.execute('cat /proc/net/snmp') ?? '';
 
     return ServerStatus(
-        cpu2Status: _getCPU(cpu, _servers[idx].status.cpu2Status!),
-        memList: _getMem(mem),
-        sysVer: sysVer.trim(),
-        disk: _getDisk(disk),
-        uptime: _getUpTime(upTime),
-        tcp: _getTcp(tcp));
+        _getCPU(cpu, _servers[idx].status.cpu2Status),
+        _getMem(mem),
+        sysVer.trim(),
+        _getUpTime(upTime),
+        _getDisk(disk),
+        _getTcp(tcp));
   }
 
   Cpu2Status _getCPU(String raw, Cpu2Status old) {