Lexer error erases last variable assignment

[Tey']

• Enter x=5. The result is 5 and x is set to 5.
• Enter @. The "invalid expression" error is shown.
• Clear the editor line and enter x. The result is 0, should be 5.

The problem is that Evaluator::eval() does not check if the call to Evaluator::evalNoAssign() failed, and since the latter does not reset m_assignId before scanning the expression (which fails), the value of the previously assigned variable is changed.

Fix on its way...

[Tey']

Do not assign variable in case of scan error. Properly rest the variable assignments properties before scanning. Fix issue #641.

→ <<cset 04d536c0d0c7>>

[Tey']

Fixed.