return 0 if cant read file

src/utils.cpp

@@ -55,6 +55,7 @@ ssize_t readFile2(std::string path, char* buffer, size_t maxlen) {
 std::string readFile(std::string path, size_t trim) {
     char buf[trim + 2];
     ssize_t len = readFile2(path, buf, trim + 2);
+    if (!len) return "0";
     std::string out(buf);
     return out.substr(0, len - 1);
 }