I keep getting a segfault somewhere in crystal-db, I'm not sure what the cause is:
```
+ crystal run tests/handlers/app_test.cr
Invalid memory access (signal 11) at address 0x0
[0x4fd4d5] *CallStack::print_backtrace:Int32 +117
[0x4e547d] __crystal_sigfault_handler +61
[0x7f2c434d8390] ???
[0x4e6711] ~DATABASE:init +17
[0x4e66f7] ~DATABASE:read +39
[0x5abec4] *Url::paginate_all<Int32, Int32>:Array(Url) +100
[0x5a4e32] *App#call<HTTP::Server::Context>:(Array(String) | Int32 | Nil) +434
[0x590f2b] *AppTest#request<String, String, Nil, Nil>:HTTP::Client::Response +107
[0x590eb5] *AppTest#request<String, String>:HTTP::Client::Response +37
[0x590e2e] *AppTest#test_get_urls:Array(JSON::Type) +46
[0x58fa54] *AppTest +868
[0x58f6e6] *AppTest::run<Minitest::AbstractReporter+>:Nil +6
[0x4e638e] ~procProc(Nil) +190
[0x533cae] *Fiber#run:(IO::FileDescriptor | Nil) +174
[0x4e5186] ~proc2Proc(Fiber, (IO::FileDescriptor | Nil)) +6
[0x0] ???
```