Suppress error logs when killing process on Windows

There is a string check here to suppress the failure logs due to this reason but on Windows, the string is different ("exit status 1").

pkg/tasks/tasks.go

@@ -277,8 +277,10 @@ func (self *ViewBufferManager) NewCmdTask(start func() (*exec.Cmd, io.Reader), p
 			refreshViewIfStale()
 
 			if err := cmd.Wait(); err != nil {
-				// it's fine if we've killed this program ourselves
-				if !strings.Contains(err.Error(), "signal: killed") {
+				select {
+				case <-opts.Stop:
+					// it's fine if we've killed this program ourselves
+				default:
 					self.Log.Errorf("Unexpected error when running cmd task: %v; Failed command: %v %v", err, cmd.Path, cmd.Args)
 				}
 			}