Segfault when accessing box before box.cfg

Steps to reproduce

Comment out everything related to box in tests
Run tests

Attempting backtrace... Note: since the server has already crashed, 
this may fail as well
#0  0x5571428e524a in crash_signal_cb+9a
#1  0x7efc173d1520 in __sigaction+50
#2  0x55714278461e in space_by_id+1e
#3  0x557142772a12 in _ZL11check_indexjjPP5spacePP5index+42
#4  0x557142773cf8 in box_index_get+28
#5  0x557142793266 in box_space_id_by_name+d6
#6  0x7efc148fa91a in _ZN9tarantool5space5Space4find17h739ca1dad641b5caE+4a
#7  0x7efc14940757 in _ZN9tarantool6schema5space12create_space17ha98348adcb8e2f9eE+67
#8  0x7efc148fa891 in _ZN9tarantool5space5Space6create17hc7cc0fdaba19bd73E+21
#9  0x7efc14831b11 in _ZN28tarantool_module_test_runner18create_test_spaces17hd2c43978d2961254E+1581
#10 0x7efc1483a73c in _ZN28tarantool_module_test_runner5start17hb9c02021a968b340E+14c
#11 0x557142954adb in lj_BC_FUNCC+34
#12 0x557142917ac5 in lua_pcall+75
#13 0x5571428cdae8 in luaT_call+18
#14 0x5571428c7c49 in lua_main+59
#15 0x5571428c8100 in run_script_f+490
#16 0x557142771321 in _ZL16fiber_cxx_invokePFiP13__va_list_tagES0_+11
#17 0x5571428eb670 in fiber_loop+30
#18 0x557142b13b54 in coro_init+44
make: *** [Makefile:5: test] Aborted (core dumped)

It's definitely an error, but it shouldn't be a segfault.