VS Code: Change color of squiggly underline for Lint

This will fix your problem.

Add "defaultSeverity": "warning"in tslint.json.

Reference: Change underline color to avoid confusion with compiler errors

VSCode v1.17 added the ability to set the color of warnings ("squiggles") and info:

Modify warning and info squiggles.

"workbench.colorCustomizations": {
  "editorWarning.foreground": "#ff0",
  "editorInfo.foreground": "#00f"
}

For eslint I was able to just set specific rules to warning, which I think is a better way to do it rather than trying to set all to one level. The unused vars was the one that really annoyed me, so:

in the .eslintrc file...

{
    "rules" : {
    "no-unused-vars": "warn"
}

There is a setting to have the tslint extension return warnings (green) instead of errors (red): "tslint.alwaysShowRuleFailuresAsWarnings": true

Also, you can change your tslint config to determine which issues are errors, and which are warnings.