beamer@doifinframe error on math

Question

I'm getting this super weird error on a normal beamer presentation with just a simple line of math and I cannot figure out how to fix it.

The error I'm getting is: Undefined control sequence. \beamer@doifinframe ... Voor alle $0 \leq t_1 \lt t_2 \lt \cdots \lt t_n \lt... l.178 \end{frame}

Here's my code:

\documentclass{beamer}

\mode<presentation>
{
 \usetheme{CambridgeUS} 
 \usecolortheme{rose} 
 \usefonttheme{structurebold}
 \setbeamertemplate{navigation symbols}{}
 \setbeamertemplate{caption}[numbered]
} 

 \usepackage[english,dutch]{babel}
 \usepackage[utf8x]{inputenc}
 \usepackage{amsmath,amssymb,amsthm,mathtools, array}
 \usepackage{graphicx}
 \usepackage{tikz}
 \usetikzlibrary{automata,positioning}
\begin{document}
\begin{frame}
Dit proces voldoet aan de Markov-eigenschap, ofwel het 'geheugenloos' zijn.\\
\begin{block}{Markov eigenschap}
Voor alle $0 \leq t_1 \lt t_2 \lt \cdots \lt t_n \lt t_{n+1}$
\begin{align*}
   P\big(X(t_{n+1})=j|X(t_{n})=i, X(t_{n-1})=i_{n-1}, \cdots, X(t_1)=i_1\big)= P\big(X(t_{n+1})=j|X(t_{n})=i\big).
\end{align*}
\end{block}
\end{frame}
\end{document}