I also have this problem and these are the logs.
[Debug] Java Home: /Library/Internet Plug-Ins/JavaAppletPlugin.plugin/Contents/Home
[Debug] Java Version: 1.8.0_181 x64 (Oracle Corporation)
[Debug] Maximum Heap Size: 683MB
[Debug] RuneMate Version: 2.98.3
[Debug] Operating System: Mac OS X x64...
