java.lang.IllegalArgumentException
at net.sourceforge.plantuml.LineLocationImpl.<init>(LineLocationImpl.java:55)
at net.sourceforge.plantuml.LineLocationImpl.<init>(LineLocationImpl.java:50)
at net.sourceforge.plantuml.syntax.SyntaxChecker.lastLineNumber2(SyntaxChecker.java:164)
at net.sourceforge.plantuml.syntax.SyntaxChecker.checkSyntaxFair(SyntaxChecker.java:126)
at org.plantuml.idea.lang.annotator.PlantUmlExternalAnnotator.checkSyntax(PlantUmlExternalAnnotator.java:121)
at org.plantuml.idea.lang.annotator.PlantUmlExternalAnnotator.annotateSyntaxErrors(PlantUmlExternalAnnotator.java:94)
at org.plantuml.idea.lang.annotator.PlantUmlExternalAnnotator.doAnnotate(PlantUmlExternalAnnotator.java:61)
at org.plantuml.idea.lang.annotator.PlantUmlExternalAnnotator.doAnnotate(PlantUmlExternalAnnotator.java:37)
https://github.com/esteinberg/plantuml4idea/issues/188