cmdtrace.c: fix segfault when trying to list trace after loading fails

client/src/cmdtrace.c

@@ -1094,8 +1094,9 @@ static int CmdTraceLoad(const char *Cmd) {
     CLIParserFree(ctx);
 
     if (gs_trace) {
-        free(gs_trace);
+        free(gs_trace);	// maybe better to not clobber this until we have successful load?
         gs_trace = NULL;
+	gs_traceLen = 0;
     }
 
     size_t len = 0;