check mbrtowc before char width calculation

Author: ryenus

CommandScreen.c

@@ -68,10 +68,15 @@ static int CommandScreen_scanWide(InfoScreen* this, const char* p, size_t total,
       } else {
          wchar_t wc;
          bytes = mbrtowc(&wc, p + i, total - i, &state);
-         width = wcwidth(wc);
-         if (bytes == (size_t)-1 || bytes == (size_t)-2 || width < 0) {
-            bytes = width = 1;
+         if (bytes != (size_t)-1 && bytes != (size_t)-2) {
+            width = wcwidth(wc);
+            if (width < 1) {
+               width = 1; // treat zero-width characters as single byte
+            }
+         } else {
+            bytes = width = 1; // invalid multibyte sequence, treat as single byte
          }
+
          memcpy(line + line_offset, p + i, bytes);
       }