runtime error: index out of range

Description of the problem or steps to reproduce

After editing files for a while, i start getting this error every time I insert a character or newline:

    runtime error: index out of range
    stack traceback:
    	[G]: ?
    
    Press enter to continue

After exiting this error message, the character is properly inserted.
After this starts happening, the issue is present in all tabs.
I also noticed micro starts using a lot of CPU some of the times.

I started micro with micro -softwrap off -syntax off -mouse off to avoid the usual suspects.
After i save the files, close and reopen them, the issue disappears.

I tried to compile micro myself in hope of a better stackstrace, but it gave me the same result. I don't know how to enable compilation with symbols or whatever the go equivalent might be.

This might be related to issue #1032, but in my case i disabled the mouse. I do however use Shift + (left, right, end or home) to select text quite a lot.

Here are my setting files.

Specifications

Version: 1.4.1
Commit hash: 1856891
Compiled on August 10, 2018
OS: Manjaro Gnome
Terminal: Both Gnome Terminal and Xterm are affected

Start by reproducing the error in micro 1.4.1 with micro -softwrap off -syntax off -mouse off, especially after repeated editing and Shift-based selection. No source file or test is named, so trace the reported index-out-of-range failure and compare behavior across tabs. Done means insertion and newline no longer trigger the error or abnormal CPU use.