Message warning in improvement suggestions

Consider the following MWE:

\documentclass{article}
\usepackage{xparse,l3draw,xcolor}

\ExplSyntaxOn
%-----------------------------------------------------------------------------
% Error handling function warning message

\msg_new:nnn { mathicon } { invalid-size }
 { Size~must~be~positive.~Using~default~of~11pt.}

\msg_new:nnn { mathicon } { invalid-shape }
 { The~shape~"#1"~is~not~recognized.~Using~a~square~by~default. }
 

%----------------------------------------------------------------------------- 
% Error handling function for size
\cs_new_protected:Nn \__mi_geo_check_size:n
 {
  \dim_compare:nNnTF {#1} > { 0pt }
   { \dim_set:Nn \l__mi_geo_size_dim {#1} }
   {
    \msg_warning:nn { mathicon } { invalid-size }
    \dim_set:Nn \l__mi_geo_size_dim { 11pt }
   }
 }
%-----------------------------------------------------------------------------
% Command to draw the shape with optional size, color, and line thickness
\NewDocumentCommand{\migeoshape}{O{ 11pt } O{ magenta } O{ 0.025 } m}
 {
  \mi_geo_draw_shape:nnnn { #4 } { #1 } { #2 } { #3 }
 }
%----------------------------------------------------------------------------- 
% Internal variables
\dim_new:N \l__mi_geo_size_dim

% Function to draw square
\cs_new_protected:Nn \mi_geo_draw_square:
 {
  \draw_path_rectangle:nn { 0.0\l__mi_geo_size_dim , 0.0\l__mi_geo_size_dim } { 1.0\l__mi_geo_size_dim, 1\l__mi_geo_size_dim }
  \draw_path_use_clear:n { stroke }
 }

%-----------------------------------------------------------------------------
% Main function to draw the shape with size, color, and line thickness
\cs_new_protected:Nn \mi_geo_draw_shape:nnnn
 {
  \__mi_geo_check_size:n { #2 }
  \draw_begin:
  \color_select:n { #3 }
  \draw_linewidth:n { #4 \l__mi_geo_size_dim }
  \str_case:nnF { #1 }
   {
    { square } { \mi_geo_draw_square: } %Use for cases. This is just for testing.
   }
   {
    \msg_warning:nnn { mathicon } { invalid-shape } { #1 }
    \mi_geo_draw_square:
   }
  \draw_end:
 }
\ExplSyntaxOff

\begin{document}
\migeoshape[-11pt][red][0.036]{square} Sample
\migeoshape[11pt][black][0.075]{hexagon} % This will default to square with a warning
\end{document}

The first warning works well, but for the second something weird happens. In the image below, (mathicon) appears in the message.

Also, if I find the message in Texmaker, the part (mathicon) square by default. goes to the next line and is not highlighted blue.

Is there a fix to this? Also I would like to add the line number to the warming message. I have not managed to succesfully use \msg_line_context:

Also, if you have any suggestions for my code improvement, let me know.