启用 trim.directive.comments 的时候，出现 NullPointerException

[subchen]

模板：

<!-- #set(String title = "") -->

开启

trim.directive.comments = true

出现 NullPointerException

java.lang.NullPointerException: null
    at jetbrick.template.parser.code.TextCode.trimEmptyLine(TextCode.java:62) ~[bin/:na]
    at jetbrick.template.parser.JetTemplateCodeVisitor.visitBlock(JetTemplateCodeVisitor.java:201) ~[bin/:na]
    at jetbrick.template.parser.JetTemplateCodeVisitor.visitBlock(JetTemplateCodeVisitor.java:1) ~[bin/:na]
    at jetbrick.template.parser.grammer.JetTemplateParser$BlockContext.accept(JetTemplateParser.java:154) ~[bin/:na]
    at jetbrick.template.parser.JetTemplateCodeVisitor.visitTemplate(JetTemplateCodeVisitor.java:148) ~[bin/:na]
    at jetbrick.template.parser.JetTemplateCodeVisitor.visitTemplate(JetTemplateCodeVisitor.java:1) ~[bin/:na]
    at jetbrick.template.parser.grammer.JetTemplateParser$TemplateContext.accept(JetTemplateParser.java:104) ~[bin/:na]
    at jetbrick.template.JetTemplate.generateJavaSource(JetTemplate.java:135) ~[bin/:na]
    at jetbrick.template.JetTemplate.compileAndLoadClass(JetTemplate.java:101) ~[bin/:na]
    at jetbrick.template.JetTemplate.<init>(JetTemplate.java:68) ~[bin/:na]
    at jetbrick.template.JetEngine$ConcurrentTemplateCache.doGetValue(JetEngine.java:179) ~[bin/:na]
    at jetbrick.template.JetEngine$ConcurrentTemplateCache.doGetValue(JetEngine.java:1) ~[bin/:na]
    at jetbrick.template.utils.ConcurrentCache.get(ConcurrentCache.java:44) ~[bin/:na]
    at jetbrick.template.JetEngine.getTemplate(JetEngine.java:92) ~[bin/:na]