Don't crash if function is not found.

elab_expr.cc

@@ -2054,6 +2054,12 @@ NetExpr* PECallFunction::elaborate_expr_method_(Design*des, NetScope*scope,
       perm_string method_name = peek_tail_name(use_path);
       use_path.pop_back();
 
+	// If there is no object to the left of the method name, then
+	// give up on the idea of looking for an object method.
+      if (use_path.empty()) {
+	    return 0;
+      }
+
       NetNet *net = 0;
       const NetExpr *par;
       NetEvent *eve;

symbol_search.cc

@@ -65,6 +65,8 @@ bool symbol_search(const LineInfo*li, Design*des, NetScope*scope,
       assert(scope);
       bool prefix_scope = false;
       bool recurse_flag = false;
+
+      ivl_assert(*li, ! path.empty());
       name_component_t path_tail = path.back();
       path.pop_back();