SIGSEGV by env.render("{{ 1 + }}", data)

[kubo]

I inserted the following line here and ran tests.

CHECK_THROWS_WITH(env.render("{{ 1 + }}", data), "???");

inja_test got SIGSEGV as follows.

$ ./inja_test 
[doctest] doctest version is "2.4.9"
[doctest] run with "--help" for options
===============================================================================
/home/kubo/inja/test/test-functions.cpp:3:
TEST CASE:  functions
  math

/home/kubo/inja/test/test-functions.cpp:3: FATAL ERROR: test case CRASHED: SIGSEGV - Segmentation violation signal

===============================================================================
/home/kubo/inja/test/test-functions.cpp:3:
TEST CASE:  functions

DEEPEST SUBCASE STACK REACHED (DIFFERENT FROM THE CURRENT ONE):
  math

===============================================================================
[doctest] test cases:  7 |  6 passed | 1 failed | 8 skipped
[doctest] assertions: 33 | 33 passed | 0 failed |
[doctest] Status: FAILURE!
Segmentation fault (core dumped)

Inserting the following code here fixes SIGSEGV.

    if (static_cast<int>(arguments.size()) < function->number_args) {
      throw_parser_error("too few arguments");
    }

[pantor]

This is now fixed with the latest commit on master. I'll look at your PR shortly. Thanks so much!