feat+fix: make compiler STRONGAAA

- FEAT: add source code length field in `fzl_reader_t` struct
- FIX: check name, lpair (lparen) and rpair (rparen) when lexing call
- FIX: check string literal termination
- FIX: increment position even on empty string to prevent infinite
lexing loop
- FIX: add string terminator in `fzl_mktoken` when allocating space for
string value
- FIX: add check for errors in recursevly called `walk`
- FIX: change source code holder from stack-stored `char[8192]` to
dynamically allocated with actual file size holder
- FIX: correct constant hasing util to hash actual string value instead
of link

src/compiler/fzl_walker.c

@@ -100,7 +100,8 @@ bool walk(fzl_walker_t *walker, fzl_node_t *node)
       // NOTE: create block env here
       if (node->list.entry_count > 0)
         for (size_t i = 0; i < node->list.entry_count; i++)
-          walk(walker, node->list.entries[i]);
+          if (!walk(walker, node->list.entries[i]))
+            return false;
       // NOTE: destroy block env here
       break;
 
@@ -109,7 +110,8 @@ bool walk(fzl_walker_t *walker, fzl_node_t *node)
       {
         for (size_t i = 0; i < node->list.entry_count; i++)
         {
-          walk(walker, node->list.entries[i]);
+          if (!walk(walker, node->list.entries[i]))
+            return false;
           push_op(walker, FZL_OPCODE_PUSHARG);
         }
       }
@@ -146,6 +148,12 @@ bool walk(fzl_walker_t *walker, fzl_node_t *node)
 // Walk entire AST recursevily
 int fzl_walk(fzl_walker_t *walker)
 {
+  if (!walker)
+  {
+    snprintf(wlast_err, sizeof(wlast_err), "walker is null");
+    return -1;
+  }
+
   bool result = walk(walker, walker->root);
   return !result && wlast_err[0] ? -1 : 0;
 }