Bus error in Shiny session

I run Shiny app using Shiny server on CentOS7. My app gets updated automatically every few seconds using reactiveTimer(). When I check it in the morning it is always erroneous, giving some weird error codes.

It is the tail of the message stack.

First, I don't get what

bus error

is coming from. Can you give me a hint?

Morevoer, this app does not use promises, but I see calling promises under the hood, is it OK?

117: promises::with_promise_domain(createStackTracePromiseDomain(),     expr)
118: captureStackTraces({    while (!.globals$stopped) {        ..stacktracefloor..(serviceApp())        Sys.sleep(0.001)    }})
119: ..stacktraceoff..(captureStackTraces({    while (!.globals$stopped) {        ..stacktracefloor..(serviceApp())        Sys.sleep(0.001)    }}))
120: runApp("main_app", port = 4701, host = "0.0.0.0")
An irrecoverable exception occurred. R is aborting now ...
Bus error