Missing closing Brace

[TomtheCoder2]

I wanted to write some sums and got this weird bug:

// Doesnt compile:
LaTeX("$\\sum\\limits_{k=1}^n k^2$")
LaTeX("$\\sum_{k=1}^n k^2$")
// compiles:
LaTeX("$\\sum\\limits_{k=1}}^n k^2$")
LaTeX("$\\sum_{k=1}}^n k^2$")
LaTeX("$\\sqrt{4}$")
LaTeX("$\\sum\\limits_{k=1}}^n k^2$")

This is the error description: