fix: Fixed ALL the code

src/lexer/lexer.c

@@ -1,13 +1,16 @@
 #include "lexer.h"
 
 #include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "io_backend/io_backend.h"
 
 static char *end_last_token;
 static ssize_t remaining_chars;
 
-char *new_token(char *begin, size_t size)
+char *new_token(char *begin, ssize_t size)
 {
     char *res = calloc(size + 1, sizeof(char));
     if (res == NULL)
@@ -56,6 +59,7 @@ char *get_token(void)
                 // skip blank char
                 // exit from loop
                 char *token = new_token(stream, i);
+                return token;
             }
         default:
             break;
@@ -64,4 +68,5 @@ char *get_token(void)
     }
 
     remaining_chars -= i;
+    return NULL;
 }