More guarding against freeing NULL pointers.

src/list.c

@@ -25,22 +25,23 @@ void
 list_free(l)
   list *l;
 {
-  list_item *li, *tmp;
+  if (l) {
+    list_item *li, *tmp;
 
-  pthread_mutex_lock(&(l->mutex));
+    pthread_mutex_lock(&(l->mutex));
 
-  if (l != NULL) {
-    li = l->head;
-    while (li != NULL) {
-      tmp = li->next;
-      zfree(li);
-      li = tmp;
+    if (l != NULL) {
+      li = l->head;
+      while (li != NULL) {
+        tmp = li->next;
+        li = tmp;
+      }
     }
-  }
 
-  pthread_mutex_unlock(&(l->mutex));
-  pthread_mutex_destroy(&(l->mutex));
-  zfree(l);
+    pthread_mutex_unlock(&(l->mutex));
+    pthread_mutex_destroy(&(l->mutex));
+    zfree(l);
+  }
 }
 
 list_item *

src/token.c

@@ -21,11 +21,15 @@ str_array * str_array_create(int cap) {
 }
 
 void str_array_free(str_array *l) {
-    for ( int i = 0; i < l->len ; i++ ) {
-        char * t = l->tokens[ i ];
-        zfree(t);
+    if (l) {
+        for ( int i = 0; i < l->len ; i++ ) {
+            char * t = l->tokens[ i ];
+            if (t) {
+                zfree(t);
+            }
+        }
+        zfree(l);
     }
-    zfree(l);
 }
 
 bool str_array_is_full(str_array * l) {