Adds null-guard to PrintIdTree

src/identcheck.c

@@ -127,6 +127,11 @@ void PrintIdNode(IdNode *node) {
 }
 
 void PrintIdTree(IdNode *tree, uint32_t tabCount) {
+    if (tree == NULL) {
+        fprintf(stderr, "wraith: Attempted to call PrintIdTree on a null value.\n");
+        return;
+    }
+
     uint32_t i;
     for (i = 0; i < tabCount; i++) {
         printf("| ");