Stack trace not useful in SQL dsl for Java

I am testing Apache Beam to be used in our company's environment. I could be missing something, but it seems the stack tracing is very limited, in particular when using the SQL dsl available for the Beam Java SDK. This makes troubleshooting more difficult. 

One minimal example shows it very well: [https://github.com/jtestard/beam-sql-stack-trace](https://github.com/jtestard/beam-sql-stack-trace) (the pom.xml in this repo should detail all dependencies used, the JDK used is Java 8). This GitHub repo gives attempts perform two back-to-back SQL transforms, the first of which contains a mismatch between input and output schema. The stack trace, however, gives little indication of the problem and does not trace to which transform the problem originated in:

`org.apache.beam.sdk.Pipeline$PipelineExecutionException: java.lang.RuntimeException: CalcFn failed to evaluate: {`
` final org.apache.beam.sdk.values.Row current = (org.apache.beam.sdk.values.Row) c.element();`
` c.output(org.apache.beam.sdk.values.Row.withSchema(outputSchema).addValue(current.getValue(0)).addValue(current.getValue(1)).build());`
` `}`at org.apache.beam.runners.direct.DirectRunner$DirectPipelineResult.waitUntilFinish(DirectRunner.java:348)`
` at org.apache.beam.runners.direct.DirectRunner$DirectPipelineResult.waitUntilFinish(DirectRunner.java:318)`
` at org.apache.beam.runners.direct.DirectRunner.run(DirectRunner.java:213)`
` at org.apache.beam.runners.direct.DirectRunner.run(DirectRunner.java:67)`
` at org.apache.beam.sdk.Pipeline.run(Pipeline.java:313)`
` at org.apache.beam.sdk.Pipeline.run(Pipeline.java:299)`
` at dummy.MainTest.testMain(MainTest.java:18)`
` at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)`
` at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)`
` at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)`
` at java.lang.reflect.Method.invoke(Method.java:498)`
` at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)`
` at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)`
` at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)`
` at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)`
` at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)`
` at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)`
` at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)`
` at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)`
` at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)`
` at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)`
` at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)`
` at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)`
` at org.junit.runners.ParentRunner.run(ParentRunner.java:363)`
` at org.junit.runner.JUnitCore.run(JUnitCore.java:137)`
` at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)`
` at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)`
` at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)`
` at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)`
` Caused by: java.lang.RuntimeException: CalcFn failed to evaluate: {`
` final org.apache.beam.sdk.values.Row current = (org.apache.beam.sdk.values.Row) c.element();`
` c.output(org.apache.beam.sdk.values.Row.withSchema(outputSchema).addValue(current.getValue(0)).addValue(current.getValue(1)).build());`
` `}`at org.apache.beam.sdk.extensions.sql.impl.rel.BeamCalcRel$CalcFn.processElement(BeamCalcRel.java:253)`
` Caused by: java.lang.RuntimeException: org.apache.beam.sdk.coders.CoderException: java.io.EOFException`
` at org.apache.beam.runners.direct.ImmutabilityCheckingBundleFactory$ImmutabilityEnforcingBundle.add(ImmutabilityCheckingBundleFactory.java:114)`
` at org.apache.beam.runners.direct.ParDoEvaluator$BundleOutputManager.output(ParDoEvaluator.java:264)`
` at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.SimpleDoFnRunner.outputWindowedValue(SimpleDoFnRunner.java:248)`
` at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.SimpleDoFnRunner.access$700(SimpleDoFnRunner.java:74)`
` at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.SimpleDoFnRunner$DoFnProcessContext.output(SimpleDoFnRunner.java:560)`
` at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.SimpleDoFnRunner$DoFnProcessContext.output(SimpleDoFnRunner.java:548)`
` at SC.eval0(Unknown Source)`
` at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)`
` at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)`
` at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)`
` at java.lang.reflect.Method.invoke(Method.java:498)`
` at org.apache.beam.sdks.java.extensions.sql.repackaged.org.codehaus.janino.ScriptEvaluator.evaluate(ScriptEvaluator.java:798)`
` at org.apache.beam.sdks.java.extensions.sql.repackaged.org.codehaus.janino.ScriptEvaluator.evaluate(ScriptEvaluator.java:790)`
` at org.apache.beam.sdk.extensions.sql.impl.rel.BeamCalcRel$CalcFn.processElement(BeamCalcRel.java:250)`
` at org.apache.beam.sdk.extensions.sql.impl.rel.BeamCalcRel$CalcFn$DoFnInvoker.invokeProcessElement(Unknown Source)`
` at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.SimpleDoFnRunner.invokeProcessElement(SimpleDoFnRunner.java:214)`
` at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.SimpleDoFnRunner.processElement(SimpleDoFnRunner.java:179)`
` at org.apache.beam.repackaged.beam_runners_direct_java.runners.core.SimplePushbackSideInputDoFnRunner.processElementInReadyWindows(SimplePushbackSideInputDoFnRunner.java:78)`
` at org.apache.beam.runners.direct.ParDoEvaluator.processElement(ParDoEvaluator.java:211)`
` at org.apache.beam.runners.direct.DoFnLifecycleManagerRemovingTransformEvaluator.processElement(DoFnLifecycleManagerRemovingTransformEvaluator.java:54)`
` at org.apache.beam.runners.direct.DirectTransformExecutor.processElements(DirectTransformExecutor.java:160)`
` at org.apache.beam.runners.direct.DirectTransformExecutor.run(DirectTransformExecutor.java:124)`
` at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)`
` at java.util.concurrent.FutureTask.run(FutureTask.java:266)`
` at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)`
` at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)`
` at java.lang.Thread.run(Thread.java:748)`
` Caused by: org.apache.beam.sdk.coders.CoderException: java.io.EOFException`
` at org.apache.beam.sdk.coders.StringUtf8Coder.decode(StringUtf8Coder.java:104)`
` at org.apache.beam.sdk.coders.StringUtf8Coder.decode(StringUtf8Coder.java:90)`
` at org.apache.beam.sdk.coders.StringUtf8Coder.decode(StringUtf8Coder.java:37)`
` at org.apache.beam.sdk.coders.RowCoderGenerator$DecodeInstruction.decodeDelegate(RowCoderGenerator.java:311)`
` at org.apache.beam.sdk.coders.Coder$ByteBuddy$Ib8rqlTB.decode(Unknown Source)`
` at org.apache.beam.sdk.coders.Coder$ByteBuddy$Ib8rqlTB.decode(Unknown Source)`
` at org.apache.beam.sdk.coders.RowCoder.decode(RowCoder.java:150)`
` at org.apache.beam.sdk.schemas.SchemaCoder.decode(SchemaCoder.java:86)`
` at org.apache.beam.sdk.coders.Coder.decode(Coder.java:159)`
` at org.apache.beam.sdk.util.CoderUtils.decodeFromSafeStream(CoderUtils.java:115)`
` at org.apache.beam.sdk.util.CoderUtils.decodeFromByteArray(CoderUtils.java:98)`
` at org.apache.beam.sdk.util.CoderUtils.decodeFromByteArray(CoderUtils.java:92)`
` at org.apache.beam.sdk.util.CoderUtils.clone(CoderUtils.java:141)`
` at org.apache.beam.sdk.util.MutationDetectors$CodedValueMutationDetector.(MutationDetectors.java:113)`
` at org.apache.beam.sdk.util.MutationDetectors.forValueWithCoder(MutationDetectors.java:44)`
` at org.apache.beam.runners.direct.ImmutabilityCheckingBundleFactory$ImmutabilityEnforcingBundle.add(ImmutabilityCheckingBundleFactory.java:112)`
` ... 26 more`
` Caused by: java.io.EOFException`
` at org.apache.beam.sdk.util.VarInt.decodeLong(VarInt.java:73)`
` at org.apache.beam.sdk.util.VarInt.decodeInt(VarInt.java:56)`
` at org.apache.beam.sdk.coders.StringUtf8Coder.readString(StringUtf8Coder.java:55)`
` at org.apache.beam.sdk.coders.StringUtf8Coder.decode(StringUtf8Coder.java:100)`
` ... 41 more`

Imported from Jira [BEAM-7756](https://issues.apache.org/jira/browse/BEAM-7756). Original Jira may contain additional context.
Reported by: jtestard.