title: FAILED: RuntimeException Hive internal error: conversion of string to void not supported yet
body: <p>NULL selection as column in a union/sub-queries failed with internal error</p>
  
  <p>Failing HIVE query:</p>
  
  <pre><code>select clientid from hivesampletable limit 1 union all select null as clientid;
  </code></pre>
  
  <pre>
  java.lang.RuntimeException: Hive internal error: conversion of string to void not supported yet.
                  at org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters.getConverter(ObjectInspectorConverters.java:132)
                  at org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorConverters.getConverter(ObjectInspectorConverters.java:152)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagateProcFactory.typeCast(ConstantPropagateProcFactory.java:178)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagateProcFactory.evaluateColumn(ConstantPropagateProcFactory.java:525)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagateProcFactory.foldExprFull(ConstantPropagateProcFactory.java:328)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagateProcFactory.foldExpr(ConstantPropagateProcFactory.java:222)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagateProcFactory.foldExprFull(ConstantPropagateProcFactory.java:296)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagateProcFactory.foldExpr(ConstantPropagateProcFactory.java:222)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagateProcFactory.access$000(ConstantPropagateProcFactory.java:93)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagateProcFactory$ConstantPropagateSelectProc.process(ConstantPropagateProcFactory.java:796)
                  at org.apache.hadoop.hive.ql.lib.DefaultRuleDispatcher.dispatch(DefaultRuleDispatcher.java:90)
                  at org.apache.hadoop.hive.ql.lib.DefaultGraphWalker.dispatchAndReturn(DefaultGraphWalker.java:94)
                  at org.apache.hadoop.hive.ql.lib.DefaultGraphWalker.dispatch(DefaultGraphWalker.java:78)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagate$ConstantPropagateWalker.walk(ConstantPropagate.java:155)
                  at org.apache.hadoop.hive.ql.lib.DefaultGraphWalker.startWalking(DefaultGraphWalker.java:109)
                  at org.apache.hadoop.hive.ql.optimizer.ConstantPropagate.transform(ConstantPropagate.java:125)
                  at org.apache.hadoop.hive.ql.optimizer.Optimizer.optimize(Optimizer.java:178)
                  at org.apache.hadoop.hive.ql.parse.SemanticAnalyzer.analyzeInternal(SemanticAnalyzer.java:10146)
                  at org.apache.hadoop.hive.ql.parse.BaseSemanticAnalyzer.analyze(BaseSemanticAnalyzer.java:221)
                  at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:417)
                  at org.apache.hadoop.hive.ql.Driver.compile(Driver.java:305)
                  at org.apache.hadoop.hive.ql.Driver.compileInternal(Driver.java:1069)
                  at org.apache.hadoop.hive.ql.Driver.runInternal(Driver.java:1131)
                  at org.apache.hadoop.hive.ql.Driver.run(Driver.java:1006)
                  at org.apache.hadoop.hive.ql.Driver.run(Driver.java:996)
                  at org.apache.hadoop.hive.cli.CliDriver.processLocalCmd(CliDriver.java:247)
                  at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:199)
                  at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:410)
                  at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:345)
                  at org.apache.hadoop.hive.cli.CliDriver.processReader(CliDriver.java:443)
                  at org.apache.hadoop.hive.cli.CliDriver.processFile(CliDriver.java:459)
                  at org.apache.hadoop.hive.cli.CliDriver.executeDriver(CliDriver.java:739)
                  at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:677)
                  at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:616)
                  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 org.apache.hadoop.util.RunJar.run(RunJar.java:221)
                  at org.apache.hadoop.util.RunJar.main(RunJar.java:136)
  </pre>