Adds error message to FindId, extra test code in main

commenttest.w

@@ -0,0 +1,6 @@
+struct Program { 
+    // This triggers a parse error
+    static Main(): int {
+        return 0;
+    }
+}

src/identcheck.c

@@ -154,6 +154,11 @@ int PrintAncestors(IdNode *node) {
 }
 
 IdNode* FindId(IdNode *root, NodeType targetType, char *targetName) {
+    if (root == NULL) {
+        fprintf(stderr, "wraith: Attempted to call FindId on a null value.\n");
+        return NULL;
+    }
+
     IdNode *result = NULL;
     IdNode **frontier = (IdNode**)malloc(sizeof(IdNode*));
     frontier[0] = root;

src/main.c

@@ -65,13 +65,21 @@ int main(int argc, char *argv[])
                 }
                 else
                 {
-                    IdNode *idTree = MakeIdTree(rootNode, NULL);
-                    PrintIdTree(idTree, /*tabCount=*/0);
-
                     {
+                        IdNode *idTree = MakeIdTree(rootNode, NULL);
+                        PrintIdTree(idTree, /*tabCount=*/0);
+                        printf("\n");
+
                         printf("Searching for a variable named 'lol' and printing its ancestors\n");
                         IdNode *deepest = FindId(idTree, Variable, "lol");
                         PrintAncestors(deepest);
+                        printf("\n");
+
+                        printf("Now searching for the same variable but with the caveat that it"
+                               " must be inside an if-block, and printing its ancestors\n");
+                        deepest = FindId(idTree, LexicalScope, "if");
+                        deepest = FindId(deepest, Variable, "lol");
+                        PrintAncestors(deepest);
                     }
                     exitCode = Codegen(rootNode, optimizationLevel);
                 }