fail javadoc task if it has errors

build.xml

@@ -694,6 +694,7 @@
             packagenames="*"
             use="true"
             splitindex="true"
+            failonerror="true"
             doctitle="I2P Javadocs for Release ${release.number} Build ${i2p.build.number}${build.extra}"
             windowtitle="I2P Anonymous Network - Java Documentation - Version ${release.number}">
             <group title="Core SDK (i2p.jar)" packages="net.i2p:net.i2p.*:net.i2p.client:net.i2p.client.*:net.i2p.internal:net.i2p.internal.*:freenet.support.CPUInformation:org.bouncycastle.oldcrypto:org.bouncycastle.oldcrypto.*:gnu.crypto.*:gnu.getopt:gnu.gettext:com.nettgryppa.security:net.metanotion:net.metanotion.*:org.apache.http.conn.ssl:org.apache.http.conn.util:org.apache.http.util" />