Hey, mod is great!
But I caught up an error. Happened when some meteorite (space exploration mod) dropped on the belt, that was attached to constant monitor (Shift + A). I guess mod doesn't expect destruction of the monitored belt. Didn't test much though.

The mod Production Analyzer (0.2.0) caused a non-recoverable error. Please report this error to the mod author.

Error while running event production-analyzer::on_nth_tick(6) LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function ' _index'
production-analyzer/analyzer/analyze.lua:150: in function 'compute_resources'
production-analyzer/analyzer/Monitor.lua:72: in function 'update_monitor'
production-analyzer/analyzer/Monitor.lua:126: in function <__production-analyzer Janalyzer/Monitorlua:110>