Fix error handling for ConnectionStringConverter.

Author: viniciusam

src/main/java/io/github/utplsql/cli/Cli.java

@@ -25,10 +25,12 @@ public static void main(String[] args) {
                 jc.usage();
             }
         } catch (ParameterException e) {
-            if (jc.getParsedCommand() != null)
+            if (jc.getParsedCommand() != null) {
+                System.err.println(e.getMessage());
                 jc.usage(jc.getParsedCommand());
-            else
+            } else {
                 jc.usage();
+            }
         } catch (Exception e) {
             e.printStackTrace();
         }

src/main/java/io/github/utplsql/cli/ConnectionStringConverter.java

@@ -1,7 +1,6 @@
 package io.github.utplsql.cli;
 
 import com.beust.jcommander.IStringConverter;
-import com.beust.jcommander.ParameterException;
 
 /**
  * Created by Vinicius on 21/04/2017.
@@ -10,10 +9,6 @@ public class ConnectionStringConverter implements IStringConverter<ConnectionInf
 
     @Override
     public ConnectionInfo convert(String s) {
-        try {
-            return new ConnectionInfo().parseConnectionString(s);
-        } catch (ParameterException ignored) {
-            return null;
-        }
+        return new ConnectionInfo().parseConnectionString(s);
     }
 }