Add missing check for return value and be more conservative in constructs to...

Add missing check for return value and be more conservative in constructs to avoid future slips of this kind.

htop.c

@@ -211,6 +211,14 @@ static bool changePriority(Panel* panel, int delta) {
    return anyTagged;
 }
 
+static int selectedPid(Panel* panel) {
+   Process* p = (Process*) Panel_getSelected(panel);
+   if (p) {
+      return p->pid;
+   }
+   return -1;
+}
+
 static Object* pickFromVector(Panel* panel, Panel* list, int x, int y, const char** keyLabels, FunctionBar* prevBar, Header* header) {
    const char* fuKeys[] = {"Enter", "Esc", NULL};
    int fuEvents[] = {13, 27};
@@ -221,8 +229,7 @@ static Object* pickFromVector(Panel* panel, Panel* list, int x, int y, const cha
    Panel* panelFocus;
    int ch;
    bool unfollow = false;
-   Process* p = (Process*)Panel_getSelected(panel);
-   int pid = p ? p->pid : -1;
+   int pid = selectedPid(panel);
    if (header->pl->following == -1) {
       header->pl->following = pid;
       unfollow = true;
@@ -237,7 +244,7 @@ static Object* pickFromVector(Panel* panel, Panel* list, int x, int y, const cha
    FunctionBar_draw(prevBar, NULL);
    if (panelFocus == list && ch == 13) {
       Process* selected = (Process*)Panel_getSelected(panel);
-      if (selected->pid == pid)
+      if (selected && selected->pid == pid)
          return Panel_getSelected(list);
       else
          beep();
@@ -465,8 +472,7 @@ int main(int argc, char** argv) {
       gettimeofday(&tv, NULL);
       newTime = ((double)tv.tv_sec * 10) + ((double)tv.tv_usec / 100000);
       recalculate = (newTime - oldTime > settings->delay);
-      Process* p = (Process*)Panel_getSelected(panel);
-      int following = (follow && p) ? p->pid : -1;
+      int following = follow ? selectedPid(panel) : -1;
       if (recalculate) {
          Header_draw(header);
          oldTime = newTime;
@@ -551,8 +557,13 @@ int main(int argc, char** argv) {
       if (isdigit((char)ch)) {
          if (Panel_size(panel) == 0) continue;
          pid_t pid = ch-48 + acc;
-         for (int i = 0; i < ProcessList_size(pl) && ((Process*) Panel_getSelected(panel))->pid != pid; i++)
+         for (int i = 0; i < ProcessList_size(pl); i++) {
             Panel_setSelected(panel, i);
+            Process* p = (Process*) Panel_getSelected(panel);
+            if (p && p->pid == pid) {
+               break;
+            }
+         }
          acc = pid * 10;
          if (acc > 10000000)
             acc = 0;