Preventing error during Latex installation on Dockerfile

docker/emacs/Dockerfile

@@ -10,7 +10,8 @@ RUN apt-get update \
 && apt-get install -y emacs	
 
 # installing texlive base with pdflatex utility:
-RUN apt-get -y install \
+RUN apt-get update \
+&& apt-get -y install \
 texlive-latex-base \
 texlive-latex-extra \
 texlive-pictures \