nullchar_tb_utf8_char_to_unicode.patch

diff --git a/termbox2.h b/termbox2.h
index a716dbd..0ec61e1 100644
--- a/termbox2.h
+++ b/termbox2.h
@@ -1816,7 +1816,12 @@ int tb_print_ex(int x, int y, uintattr_t fg, uintattr_t bg, size_t *out_w,
         *out_w = 0;
     }
     while (*str) {
-        str += tb_utf8_char_to_unicode(&uni, str);
+        if ((rv = tb_utf8_char_to_unicode(&uni, str)) == TB_ERR) {
+            uni = (uint32_t)*str;
+            str += 1;
+        } else {
+            str += rv;
+        }
         w = wcwidth((wchar_t)uni);
         if (w < 0) {
             w = 1;
@@ -1893,7 +1898,7 @@ int tb_utf8_char_length(char c) {
 }
 
 int tb_utf8_char_to_unicode(uint32_t *out, const char *c) {
-    if (*c == 0) {
+    if (*c == '\0') {
         return TB_ERR;
     }
 
@@ -1901,11 +1906,15 @@ int tb_utf8_char_to_unicode(uint32_t *out, const char *c) {
     unsigned char len = tb_utf8_char_length(*c);
     unsigned char mask = utf8_mask[len - 1];
     uint32_t result = c[0] & mask;
-    for (i = 1; i < len; ++i) {
+    for (i = 1; i < len && c[i] != '\0'; ++i) {
         result <<= 6;
         result |= c[i] & 0x3f;
     }
 
+    if (i != len) {
+        return TB_ERR;
+    }
+
     *out = result;
     return (int)len;
 }