Reproduction steps:
1. Open the attached "case_1272391.zip" project
2. Enter Play mode
-- Observe the crash

Reproducible with: 0.9.0-preview.6 (2019.4.10f1, 2020.1.5f1, 2020.2.0b2), 0.14.0-preview.18 (2019.4.10f1, 2020.1.5f1, 2020.2.0b2)
Not reproducible with: 0.8.0-preview.8 (2019.4.10f1, 2020.1.5f1, 2020.2.0b2)
Could not test with: 2018.4 (no Entities package)

Notes:
- the following assertion message always appears before the crash: * Assertion at ..\mono\mini\method-to-ir.c:8478, condition `!mono_method_check_context_used (cmethod)' not met
- in 2019.4 and 2020.1 the Editor crashes silently without any stack trace
- the crash seems to be caused by a generic method GetSingletonEntity<BufferTag<T>>(); (line 11 in ServerTransportSystem.cs)

Top 5 lines of the stack trace:
0x00007FFC39499689 (KERNELBASE) RaiseException
0x00007FFBDD4C6025 (mono-2.0-bdwgc) [c:\build\output\unity-technologies\mono\mono\utils\mono-log-common.c:142] mono_log_write_logfile
0x00007FFBDD4B4CC3 (mono-2.0-bdwgc) [c:\build\output\unity-technologies\mono\mono\eglib\goutput.c:141] monoeg_assertion_message
0x00007FFBDD60CBDE (mono-2.0-bdwgc) [c:\build\output\unity-technologies\mono\mono\mini\method-to-ir.c:8478] mono_method_to_ir
0x00007FFBDD5D42B9 (mono-2.0-bdwgc) [c:\build\output\unity-technologies\mono\mono\mini\mini.c:3465] mini_method_compile