Wrong input at special types parameters (ex: Rounding.Down) provokes a parsing exception instead of error

[Ikelio]

Entering an incorrect value in place of the expected specific type parameter can cause a parsing exception.

While it's usually an indication of a syntax error (ex: RoundToInteger(1, ()), I encountered this issue with RoundToInteger(1, ((t == 1) ? Rounding.Down : Rounding.Up)), instead of an error related to the fact that the type Rounding can't be stored.

The difference is that in opposition with a syntax error, the method containing the code need to be called to throw the exception.

Basic code to reproduce:

globalvar define t;

rule: "t"
{
    exception2();
}

method exception2()
{
    t = RoundToInteger(1, ((t == 1) ? Rounding.Down : Rounding.Up));
}

 An exception was thrown while parsing.
 System.Exception: Expression tree result is null
    at Deltin.Deltinteger.Parse.ExpressionTree.ParseTree(ActionSet actionSet, Boolean expectingValue, Boolean asElement) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\Expression.cs:line 198
    at Deltin.Deltinteger.Parse.ExpressionTree.Parse(ActionSet actionSet, Boolean asElement) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\Expression.cs:line 125
    at Deltin.Deltinteger.Parse.TernaryConditionalAction.Parse(ActionSet actionSet, Boolean asElement) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\Expression.cs:line 506
    at Deltin.Deltinteger.Parse.CodeParameter.Parse(ActionSet actionSet, IExpression expression, Boolean asElement) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\Parameter.cs:line 66
    at Deltin.Deltinteger.Parse.CallMethodAction.GetParameterValuesAsWorkshop(ActionSet actionSet) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\CallMethod.cs:line 86
    at Deltin.Deltinteger.Parse.CallMethodAction.Parse(ActionSet actionSet, Boolean asElement) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\CallMethod.cs:line 78
    at Deltin.Deltinteger.Parse.SetVariableAction.Translate(ActionSet actionSet) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\SetVariable.cs:line 82
    at Deltin.Deltinteger.Parse.BlockAction.Translate(ActionSet actionSet) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\Block.cs:line 29
    at Deltin.Deltinteger.Parse.DefinedMethod.Parse(ActionSet actionSet, IWorkshopTree[] parameterValues, Object[] additionalParameterData) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\DefinedFunctions.cs:line 220
    at Deltin.Deltinteger.Parse.CallMethodAction.Translate(ActionSet actionSet) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\CallMethod.cs:line 73
    at Deltin.Deltinteger.Parse.BlockAction.Translate(ActionSet actionSet) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\Block.cs:line 29
    at Deltin.Deltinteger.Parse.TranslateRule..ctor(DeltinScript deltinScript, RuleAction ruleAction) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\TranslateRule.cs:line 43
    at Deltin.Deltinteger.Parse.DeltinScript.ToWorkshop(Func``2 addRules) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\Translate.cs:line 224
    at Deltin.Deltinteger.Parse.DeltinScript..ctor(FileGetter fileGetter, Diagnostics diagnostics, ScriptFile rootRuleset, Func``2 addRules) in PROJECT_PATH\Deltinteger\Deltinteger\Parse\Translate.cs:line 47
    at Deltin.Deltinteger.LanguageServer.DocumentHandler.Update() in PROJECT_PATH\Deltinteger\Deltinteger\Language Server\DocumentHandler.cs:line 179

Thank you for the tool btw !