string index out of bounds leads to build not being finished

Question

In my android studio I'm not able to see my xml editor preview, everytime I try to see the window it displays this message: "waiting for build to finish". I suspect it to be the cause of a String index out of bounds exeption I'm having everytime I start up my android studio.

String index out of bounds exeption:

String index out of range: 0
java.lang.StringIndexOutOfBoundsException: String index out of range: 0
    at java.lang.String.charAt(String.java:658)

full stacktrace:

https://pastebin.com/t0XnjTFL

also autocompletion is somehow disabled (even tough it is turned on) in my xml editor.