[B136 Dev6 Linux] "Parameter 'filePath' is missing" exception happens

Steps to reproduce:
1: Open AlgoWizard
2: Click "Files" and select "Load from file..."
3: "Select" dialog appears, then click "Cancel" soon.
4: "Parameter 'filePath' is missing" exception happens.


01:54:08.654 [qtp2107760645-640] ERROR c.s.w.servlet.HttpJSONServlet - Loading failed. <br>Parameter 'filePath' is missing.
java.lang.Exception: Parameter 'filePath' is missing.
at com.strategyquant.webguilib.servlet.AbstractServlet.tryGetParam(Unknown Source) ~[SQWebGUILib.jar:na]
at com.strategyquant.plugin.Servlet.impl.AlgoWizard.AlgoWizardServlet.onLoadFile(Unknown Source) ~[na:na]
at com.strategyquant.plugin.Servlet.impl.AlgoWizard.AlgoWizardServlet.execute(Unknown Source) ~[na:na]
at com.strategyquant.webguilib.servlet.HttpJSONServlet.doGet(Unknown Source) ~[SQWebGUILib.jar:na]
at com.strategyquant.webguilib.servlet.AbstractServlet.doPost(Unknown Source) ~[SQWebGUILib.jar:na]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707) ~[jetty-all-uber.jar:9.4.19.v20190610]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:876) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:542) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1711) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1347) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:203) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:480) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1678) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:201) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1249) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:144) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.gzip.GzipHandler.handle(GzipHandler.java:753) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:61) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.Server.handle(Server.java:505) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:370) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:267) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:305) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:333) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:310) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:168) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:126) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:366) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:781) ~[jetty-all-uber.jar:9.4.19.v20190610]
at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:917) ~[jetty-all-uber.jar:9.4.19.v20190610]
at java.base/java.lang.Thread.run(Thread.java:832) ~[na:na]