java.lang.NullPointerException
at ch.qos.logback.classic.pattern.ThrowableProxyConverter.start(ThrowableProxyConverter.java:75)
at ch.qos.logback.core.pattern.ConverterUtil.startConverters(ConverterUtil.java:37)
at ch.qos.logback.core.pattern.ConverterUtil.startConverters(ConverterUtil.java:33)
at ch.qos.logback.core.pattern.PatternLayoutBase.start(PatternLayoutBase.java:89)