assertion in editor

[huguesv]

Type the following code:

x <- rnorm(10, sd = 5, mean = 20)
y <- 2.5*

When you type the *, you will get this assertion:

---------------------------
Assertion Failed: Abort=Quit, Retry=Debug, Ignore=Continue
---------------------------
Children collection already contains this node



   at Microsoft.R.Core.AST.AstNode.AppendChild(IAstNode child) in C:\Projects\GitHub\huguesv\RTVS\src\R\Core\Impl\AST\AstNode.cs:line 67

   at Microsoft.R.Core.AST.AstNode.set_Parent(IAstNode value) in C:\Projects\GitHub\huguesv\RTVS\src\R\Core\Impl\AST\AstNode.cs:line 49

   at Microsoft.R.Core.AST.AstNode.AppendChild(IAstNode child) in C:\Projects\GitHub\huguesv\RTVS\src\R\Core\Impl\AST\AstNode.cs:line 63

   at Microsoft.R.Core.AST.Expressions.ExpressionParser.MakeNode() in C:\Projects\GitHub\huguesv\RTVS\src\R\Core\Impl\AST\Expressions\ExpressionParser.cs:line 433

   at Microsoft.R.Core.AST.Expressions.ExpressionParser.ProcessHigherPrecendenceOperators(IOperator currentOperator) in C:\Projects\GitHub\huguesv\RTVS\src\R\Core\Impl\AST\Expressions\ExpressionParser.cs:line 385

   at Microsoft.R.Core.AST.Expressions.ExpressionParser.Parse(ParseContext context, IAstNode parent) in C:\Projects\GitHub\huguesv\RTVS\src\R\Core\Impl\AST\Expressions\ExpressionPa......

<truncated>
---------------------------
Abort   Retry   Ignore   
---------------------------

[MikhailArkhipov]

Fixed. Added handling of the missing operand at the end of the file + test.