fix: fix testing code

test/fuzzy.h

@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <stdbool.h>
 #include <string.h>
+#include <stdio.h>
 
 typedef struct fuzzyconfig {
     int seed;
@@ -29,12 +30,14 @@ void random_clean_string(char* s, int len) {
 }
 
 void random_string(char* s, int len) {
-    // len - 1 ensures that we can still set the null byte for the final byte
-    int val;
+    int val = rand();
 
-    for (int i = 0; i < len - 1; i++) {
+    // String can't be an empty string as they aren't supported
+    s[0] = (char)(val % 255 + 1);
+
+    for (int i = 1; i < len - 1; i++) {
         val = rand();
-        s[i] = ((char *) &val)[0];
+        s[i] = (char)(val % 256);
     }
 
     // Just in case no null characters were created