Expected: I expect to see a list of account which I could invite
Result: Uncaught SyntaxError: Invalid regular expression: /(+)/: Nothing to repeat
converse.min.js:275 Uncaught SyntaxError: Invalid regular expression: /(+)/: Nothing to repeat
at new RegExp (<anonymous>)
at a.ITEM [as item] (converse.min.js:275)
at converse.min.js:275
at Array.forEach (<anonymous>)
at a.evaluate (converse.min.js:275)
a.ITEM @ converse.min.js:275
(anonymous) @ converse.min.js:275
evaluate @ converse.min.js:275
converse.min.js:275 Uncaught SyntaxError: Invalid regular expression: /(+4)/: Nothing to repeat
at new RegExp (<anonymous>)
at a.ITEM [as item] (converse.min.js:275)
at converse.min.js:275
at Array.forEach (<anonymous>)
at a.evaluate (converse.min.js:275)
a.ITEM @ converse.min.js:275
(anonymous) @ converse.min.js:275
evaluate @ converse.min.js:275
converse.min.js:275 Uncaught SyntaxError: Invalid regular expression: /(+49)/: Nothing to repeat
at new RegExp (<anonymous>)
at a.ITEM [as item] (converse.min.js:275)
at converse.min.js:275
at Array.forEach (<anonymous>)
at a.evaluate (converse.min.js:275)

Thanks for the bug report.
This is a bug in awesomplete.js and the fix should be made upstream in that project.
Relevant debug output:
VM420:1 Uncaught SyntaxError: Unexpected string
at _.ITEM [as item] (awesomplete.js:329)
at awesomplete.js:289
at Array.forEach (<anonymous>)
at _.evaluate (awesomplete.js:288)
_.ITEM @ awesomplete.js:329
(anonymous) @ awesomplete.js:289
evaluate @ awesomplete.js:288
I'm not going to fix this within converse.js nor am I going to make an attempt to fix it in awesomplete.js. I recommend you contact that project directly.