Description
Writing the code with no spaces between the arguments of "\Edge[h local options i](Vertex i)(Vertex j)" normally handles processing:
\documentclass{article}
\usepackage {tikz-network}
\thispagestyle {empty}
\begin {document}
\begin {tikzpicture}
\Vertex{A} \Vertex [x = 2] {B} \Vertex [x = 2, y = -1] {C}
\Edge [lw = 3pt] (A) (B)
\Edge [lw = 5pt] (A) (C)
\end {tikzpicture}
\end {document}
But if there is spacing (whatever that is) between the arguments of "\Edge[h local options i](Vertex i)" as shown below:
\documentclass{article}
\usepackage{tikz-network}
\thispagestyle {empty}
\begin {document}
\begin {tikzpicture}
\Vertex {A} \Vertex [x = 2] {B} \Vertex [x = 2, y = -1] {C}
% Case 1: space between <[lw = 3pt]> and <(A)(B)>
\Edge [lw = 3pt] (A)(B)
% Case 2 (below): or even if there is a space between <(A)> and <(C)> as below
\Edge[lw = 5pt](A) (C)
\end {tikzpicture}
\end {document}
I get the following errors in their order as is the spacing in the code above:
Case 1 - Space between <[lw = 3pt]> and <(A)(B)> returns the following error:
Runaway argument?
(A)(B) \ end {tikzpicture} \ end {document}
! File ended while scanning use of \ @edge.
<inserted text>
\pair
<*> 17.tex
?
Case 2 - Space between <[lw = 5pt] (A)> and <(C)> returns the following error:
! Undefined control sequence.
\ pgfonlayer @ assert @ is @ active ... fonlayer @ isactive
{0} \ expandfter \ pgf @ asser ...
1.8 \ Edge [lw = 5pt] (A) (C)
?
Note 1: Putting spacing between <\Edge> and <[h local options i](Vertex i)(Vertex j)> returns no error.
Note 2: Examples taken from Section 2.2, page 15 of https://ctan.org/pkg/tikz-network.
Note 3: Command latexmk and Zathura viewer were used.
Apparently everything is related to using the lw (\Edge line width size) option.
Note 4: As advised at https://tex.stackexchange.com/a/501300/178949 by user TeXnician there is apparently a guideline in the code script preventing the inclusion of spacing.