maticon shows error in html code code example
Example 1: mat-icon showing text
It will always try to load the local version of "Material Icons" font
first, before the web font. Therefore, if OP has an outdated or
customized version of "Material Icons", the desired effect won't be
shown.
To fix this, delete the local "Material Icons" font, or replace it
with the latest version if you still want a local copy.
Example 2: mat icon not working
@import url("https://fonts.googleapis.com/icon?family=Material+Icons");