Improve ScreenManager_drawScreenTabs() logic on screen width

Make the code more robust with very small width of the terminal screen.
Also add assertions on x positions in the drawTab() subroutine.

Author: Explorer09

ScreenManager.c

@@ -161,6 +161,9 @@ static void checkRecalculation(ScreenManager* this, double* oldTime, int* sortTi
 }
 
 static inline bool drawTab(const int* y, int* x, int l, const char* name, bool cur) {
+   assert(*x >= 0);
+   assert(*x < l);
+
    attrset(CRT_colors[cur ? SCREENS_CUR_BORDER : SCREENS_OTH_BORDER]);
    mvaddch(*y, *x, '[');
    (*x)++;
@@ -190,9 +193,12 @@ static void ScreenManager_drawScreenTabs(ScreenManager* this) {
    int y = panel->y - 1;
    int x = SCREEN_TAB_MARGIN_LEFT;
 
+   if (x >= l)
+      goto end;
+
    if (this->name) {
       drawTab(&y, &x, l, this->name, true);
-      return;
+      goto end;
    }
 
    for (int s = 0; screens[s]; s++) {
@@ -201,6 +207,8 @@ static void ScreenManager_drawScreenTabs(ScreenManager* this) {
          break;
       }
    }
+
+end:
    attrset(CRT_colors[RESET_COLOR]);
 }