jpeek: 500 error for valid package

I’m trying to display the badge for https://github.com/g4s8/matchers-json/ project, the artifact was deployed to maven central successfully: https://search.maven.org/artifact/wtf.g4s8/matchers-json/1.0.2/jar

but when I try to open report for that project, I’m getting 500 error with stacktrace:

java.lang.IllegalStateException: [GET http://i.jpeek.org/wtf.g4s8/matchers-json/index.html] failed in 0ms: NULL instead of a valid result
	at org.takes.facets.fallback.TkFallback.error(TkFallback.java:233)
	at org.takes.facets.fallback.TkFallback.route(TkFallback.java:112)
	at org.takes.facets.fallback.TkFallback.access$000(TkFallback.java:54)
	at org.takes.facets.fallback.TkFallback$1.act(TkFallback.java:66)
	at org.takes.tk.TkWrap.act(TkWrap.java:61)
	at org.takes.tk.TkWrap.act(TkWrap.java:61)
	at org.takes.http.BkBasic.print(BkBasic.java:108)
	at org.takes.http.BkBasic.accept(BkBasic.java:84)
	at org.takes.http.BkSafe$1.accept(BkSafe.java:51)
	at org.takes.http.BkWrap.accept(BkWrap.java:52)
	at org.takes.http.BkTimeable.accept(BkTimeable.java:89)
	at org.takes.http.BkParallel$1$1.run(BkParallel.java:89)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.IllegalStateException: NULL instead of a valid result
	at org.cactoos.BiFunc$NoNulls.apply(BiFunc.java:91)
	at org.cactoos.func.IoCheckedBiFunc.lambda$apply$0(IoCheckedBiFunc.java:58)
	at org.cactoos.scalar.CheckedScalar.value(CheckedScalar.java:76)
	at org.cactoos.scalar.IoCheckedScalar.value(IoCheckedScalar.java:63)
	at org.cactoos.func.IoCheckedBiFunc.apply(IoCheckedBiFunc.java:59)
	at org.jpeek.web.TkReport.act(TkReport.java:73)
	at org.takes.facets.fork.FkRegex.route(FkRegex.java:209)
	at org.takes.facets.fork.FkChain.route(FkChain.java:75)
	at org.takes.facets.fork.TkFork.act(TkFork.java:100)
	at org.takes.facets.forward.TkForward.act(TkForward.java:68)
	at org.takes.facets.fallback.TkFallback.route(TkFallback.java:85)
	... 13 more