Misleading exception message if the number of arguments of a nested function is incorrect

@Test
def myTest(): Unit = {
  testSqlApi(s"IFNULL(SUBSTR('abc'), 'def')", "abc")
}

org.apache.flink.table.api.ValidationException: SQL validation failed. Unexpected error in type inference logic of function 'IFNULL'. This is a bug.

	at org.apache.flink.table.planner.calcite.FlinkPlannerImpl.org$apache$flink$table$planner$calcite$FlinkPlannerImpl$$validate(FlinkPlannerImpl.scala:155)
	at org.apache.flink.table.planner.calcite.FlinkPlannerImpl.validate(FlinkPlannerImpl.scala:108)
	at org.apache.flink.table.planner.expressions.utils.ExpressionTestBase.org$apache$flink$table$planner$expressions$utils$ExpressionTestBase$$addSqlTestExpr(ExpressionTestBase.scala:282)
	at org.apache.flink.table.planner.expressions.utils.ExpressionTestBase.testSqlApi(ExpressionTestBase.scala:188)
	at org.apache.flink.table.planner.expressions.ScalarFunctionsTest.myTest(ScalarFunctionsTest.scala:4067)
	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$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
	at org.junit.rules.ExpectedException$ExpectedExceptionStatement.evaluate(ExpectedException.java:239)
	at org.junit.rules.RunRules.evaluate(RunRules.java:20)
	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$2.evaluate(ParentRunner.java:268)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
Caused by: org.apache.flink.table.api.TableException: Unexpected error in type inference logic of function 'IFNULL'. This is a bug.
	at org.apache.flink.table.types.inference.TypeInferenceUtil.createUnexpectedException(TypeInferenceUtil.java:203)
	at org.apache.flink.table.planner.functions.inference.TypeInferenceOperandInference.inferOperandTypes(TypeInferenceOperandInference.java:74)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.inferUnknownTypes(SqlValidatorImpl.java:1907)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.expandSelectItem(SqlValidatorImpl.java:419)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.validateSelectList(SqlValidatorImpl.java:4061)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.validateSelect(SqlValidatorImpl.java:3347)
	at org.apache.calcite.sql.validate.SelectNamespace.validateImpl(SelectNamespace.java:60)
	at org.apache.calcite.sql.validate.AbstractNamespace.validate(AbstractNamespace.java:84)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.validateNamespace(SqlValidatorImpl.java:997)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.validateQuery(SqlValidatorImpl.java:975)
	at org.apache.calcite.sql.SqlSelect.validate(SqlSelect.java:232)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.validateScopedExpression(SqlValidatorImpl.java:952)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.validate(SqlValidatorImpl.java:704)
	at org.apache.flink.table.planner.calcite.FlinkPlannerImpl.org$apache$flink$table$planner$calcite$FlinkPlannerImpl$$validate(FlinkPlannerImpl.scala:150)
	... 30 more
Caused by: org.apache.calcite.runtime.CalciteContextException: From line 1, column 15 to line 1, column 27: Invalid number of arguments to function 'SUBSTR'. Was expecting 2 arguments
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.apache.calcite.runtime.Resources$ExInstWithCause.ex(Resources.java:467)
	at org.apache.calcite.sql.SqlUtil.newContextException(SqlUtil.java:883)
	at org.apache.calcite.sql.SqlUtil.newContextException(SqlUtil.java:868)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.newValidationError(SqlValidatorImpl.java:4861)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.handleUnresolvedFunction(SqlValidatorImpl.java:1804)
	at org.apache.calcite.sql.SqlFunction.deriveType(SqlFunction.java:321)
	at org.apache.calcite.sql.SqlFunction.deriveType(SqlFunction.java:226)
	at org.apache.calcite.sql.validate.SqlValidatorImpl$DeriveTypeVisitor.visit(SqlValidatorImpl.java:5710)
	at org.apache.calcite.sql.validate.SqlValidatorImpl$DeriveTypeVisitor.visit(SqlValidatorImpl.java:5697)
	at org.apache.calcite.sql.SqlCall.accept(SqlCall.java:139)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.deriveTypeImpl(SqlValidatorImpl.java:1736)
	at org.apache.calcite.sql.validate.SqlValidatorImpl.deriveType(SqlValidatorImpl.java:1727)
	at org.apache.flink.table.planner.functions.inference.CallBindingCallContext$1.get(CallBindingCallContext.java:69)
	at org.apache.flink.table.planner.functions.inference.CallBindingCallContext$1.get(CallBindingCallContext.java:64)
	at java.util.AbstractList$Itr.next(AbstractList.java:358)
	at java.util.Iterator.forEachRemaining(Iterator.java:116)
	at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
	at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
	at org.apache.flink.table.types.inference.strategies.CommonArgumentTypeStrategy.inferArgumentType(CommonArgumentTypeStrategy.java:58)
	at org.apache.flink.table.types.inference.strategies.SequenceInputTypeStrategy.inferInputTypes(SequenceInputTypeStrategy.java:76)
	at org.apache.flink.table.planner.functions.inference.TypeInferenceOperandInference.inferOperandTypesOrError(TypeInferenceOperandInference.java:90)
	at org.apache.flink.table.planner.functions.inference.TypeInferenceOperandInference.inferOperandTypes(TypeInferenceOperandInference.java:70)
	... 42 more
Caused by: org.apache.calcite.sql.validate.SqlValidatorException: Invalid number of arguments to function 'SUBSTR'. Was expecting 2 arguments
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at org.apache.calcite.runtime.Resources$ExInstWithCause.ex(Resources.java:467)
	at org.apache.calcite.runtime.Resources$ExInst.ex(Resources.java:560)
	... 67 more