title: Unable to activate Dart Devtools
body: <p><a href="https://i.stack.imgur.com/bLhok.png" rel="noreferrer">enter image description here</a>On opening dart devtools in VS its showing Dart devtools exited with code 255 . 
  I even tried to activating it from terminal in VS by typing <em>flutter pub global activate devtools</em> but its showing could not find a command named “global” for “flutter pub”
  <a href="https://i.stack.imgur.com/bLhok.png" rel="noreferrer">error shown on terminal</a> 
  <a href="https://i.stack.imgur.com/VWTgU.png" rel="noreferrer">error again shown after activating devtools</a></p>