Ctrl-R Insert Mode places register one char before last

If I am in insert mode and have so far typed

"text"

I then type a to paste the contents of the a register ("AREG"), I get the a register pasted before the final t instead of after it

"texAREGt" instead of "textAREG"

This only occurs when I am at the last character of the line, not when in the middle. For example, if I am in the middle of following line, and enter Insert mode and type "texta", the put text is the correct position.

"This line of textAREG is here"

If I disable peekaboo, the issue is corrected.

Reproduce the issue in insert mode with peekaboo enabled by typing text followed by Ctrl-R a at the end of a line, then compare with peekaboo disabled. Inspect the plugin's insert-mode handling and verify that the register contents are inserted after the final character without changing behavior in the middle of a line.

Written by the indexing model from the issue text.