fix: set error status flag based on exit code

- Modify setExitCode function to use actual exit code value for error status
- When exit code is 0 (success), do not set error flag
- When exit code is non-zero (failure), set error flag

src/Screen.cpp

@@ -2512,11 +2512,11 @@ void Screen::setReplMode(int mode)
     }
 }
 
-void Screen::setExitCode(int /*exitCode*/)
+void Screen::setExitCode(int exitCode)
 {
     int y = _cuY - 1;
     while (y >= 0) {
-        _lineProperties[y].flags.f.error = 1;
+        _lineProperties[y].flags.f.error = (exitCode != 0);
         if (_lineProperties[y].flags.f.prompt_start) {
             return;
         }