The bug

The parameter count of the /particle command changes depending on the used particle (see also MC-122181). While the command syntax help at least colors the additional parameters in the same color as the particle name, text editors and currently command blocks do not do that. This makes it rather hard to understand what the arguments mean unless you know all parameter a particle has by heart. Additionally it prevents leaving out a parameter to use a default value.

Something like the following might be better:

dust[r=1.0,g=1.0,b=1.0,size=1.0]
dust[color={r=1.0,g=1.0,b=1.0},size=1.0]

How to reproduce

Type the following

/particle dust

→ The next parameter is suddenly not the x-coordinate anymore but instead the r-color value