Change the way errors are presented in the log file

Currently, for any log level, the error code will be appended to the line in the log file. Usually, that's code 0:

In case of errors, the log line still starts with the original log level but has a non-zero error code:

For most errors, there will be line breaks in the actual error message:

Suggestion:

Prepend the original log level with "ERROR" (if it isn't error already) and do not print the ''- 0 -'' (no error):

Maybe, we should remove all line breaks from the error string to avoid creating new lines in the log