From mcufont upstream: Fix inconsistency between UTF8 and other encodings

src/gdisp/mcufont/mf_encoding.c

@@ -75,11 +75,16 @@ void mf_rewind(mf_str *str)
 
 #else
 
-mf_char mf_getchar(mf_str *str) {
-	return *(*str)++;
+mf_char mf_getchar(mf_str *str)
+{
+    if (!(**str))
+        return 0;
+    else
+        return *(*str)++;
 }
 
-void mf_rewind(mf_str *str) {
+void mf_rewind(mf_str *str)
+{
 	(*str)--;
 }