Describe the bug

Any attempt to change $theme-text-color to anything other than 'ink' leads to an error.

From @aduth

It does seem like there might be a bug here, in that this code expects to find icons of various alert types (warning, etc) in the img/alerts folder ending in -white, but there’s only the error icon there.

Steps to reproduce the bug

1. Change the value of $theme-text-color to anything other than ink
2. Look at the info alert, it will no longer have an icon and there will be an error in the console

This may affect more than just the alert.

Expected behavior

In addition to updating the text color, the system should be able to display icons that match the theme color in relevant components.

Additional context

We want to use our color icon mixins to place these icons into an alert.