Do not terminate algorithm for exceptions in GDAX Fill Monitor (#4910)
Do not terminate algorithm for exceptions in GDAX Fill Monitor (#4910)

* Do not terminate algorithm for exceptions in GDAX Fill Monitor

* Address review

- Only emit warning for REST API errors, other errors are fatal
JKarathiya/Lean,JKarathiya/Lean,StefanoRaggi/Lean,jameschch/Lean,AlexCatarino/Lean,StefanoRaggi/Lean,jameschch/Lean,jameschch/Lean,StefanoRaggi/Lean,AlexCatarino/Lean,jameschch/Lean,AlexCatarino/Lean,QuantConnect/Lean,QuantConnect/Lean,StefanoRaggi/Lean,AlexCatarino/Lean,JKarathiya/Lean,JKarathiya/Lean,QuantConnect/Lean,QuantConnect/Lean,jameschch/Lean,StefanoRaggi/Lean