sqlline should give an error message and not throw a NPE

[khurram-faraaz]

Use of -u instead of -n option to sqlline results in a NPE, sqlline should report an error and not throw a NPE.

{noformat}
[root@centos-01 ~]# cd /opt/mapr/drill/drill-1.10.0/bin
[root@centos-01 bin]# ./sqlline -u "jdbc:drill:schema=dfs.tmp;drillbit=10.10.100.201" -u mapr -p mapr
...
...
No known driver to handle "mapr". Searching for known drivers...
java.lang.NullPointerException
apache drill 1.10.0-SNAPSHOT
"what ever the mind of man can conceive and believe, drill can query"
0: mapr> !q
No known driver to handle "mapr". Searching for known drivers...
java.lang.NullPointerException
at sqlline.DatabaseConnection.connect(DatabaseConnection.java:167)
at sqlline.DatabaseConnection.getConnection(DatabaseConnection.java:213)
at sqlline.Commands.close(Commands.java:925)
at sqlline.Commands.quit(Commands.java:889)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at sqlline.ReflectiveCommandHandler.execute(ReflectiveCommandHandler.java:36)
at sqlline.SqlLine.dispatch(SqlLine.java:742)
at sqlline.SqlLine.begin(SqlLine.java:621)
at sqlline.SqlLine.start(SqlLine.java:375)
at sqlline.SqlLine.main(SqlLine.java:268)
No known driver to handle "mapr". Searching for known drivers...
java.lang.NullPointerException
at sqlline.DatabaseConnection.connect(DatabaseConnection.java:167)
at sqlline.DatabaseConnection.getConnection(DatabaseConnection.java:213)
at sqlline.Commands.close(Commands.java:925)
at sqlline.Commands.closeall(Commands.java:899)
at sqlline.SqlLine.begin(SqlLine.java:649)
at sqlline.SqlLine.start(SqlLine.java:375)
at sqlline.SqlLine.main(SqlLine.java:268)

{noformat}

[julianhyde]

Fixed in 0b0be19, PR #116. Thanks @arina-ielchiieva!