Fix exception logging

[lchen-2101]

We're logging exceptions incorrectly in some areas of the code.
e.g.

try:
    ...
except Exception as e:
    log.error("some custom message", e)

This would cause the error not all arguments converted during string formatting, which is because in the example, subsequent unnamed arguments are expected to be part of interpolated string for the custom message.
e.g.

log.error("some custom message with variable: %s", some_variable)

We can log just the exception without custom message:

try:
    ...
except Exception as e:
    log.error(e)

however to log the exception with additional custom message, we should be doing:

try:
    ...
except Exception as e:
    log.exception("some custom message")

log.exception("some message") is the equivalent to log.error("some message", exc_info=True), which having exc_info set to true causes the exception information to be added to the log message. Additionally, we can add stack_info=True to the logging parameters to show the unwound stack leading up to the logging call (not the same as exception stack trace).