Imports in .d.ts files break wildcard modules declarations

TypeScript Version: 3.1.3

Search Terms:

import d.ts wildcard module

Code

main.ts

/// <reference path="./typings.d.ts" />

import template from './template.html';

typings.d.ts

import * as _angular from 'angular';

declare module '*.html' {
  const content : string;
  export default content;
}

{
  "name": "ts-bug",
  "version": "1.0.0",
  "dependencies": {
    "angular": "^1.7.5"
  }
}

Compile with:

tsc main.ts

Expected behavior:

Compiled without errors.

Actual behavior:
Compiled with error

main.ts:3:22 - error TS2307: Cannot find module './template.html'.

3 import template from './template.html';
                       ~~~~~~~~~~~~~~~~~

Removing import * as _angular from 'angular'; fixes the issue.

Side Note 1

Regular module declarations work regardless of imports being present.

Side Note 2
import * as _angular from 'angular'; is needed to later do:

declare global {
  const angular : typeof _angular;
}

to workaround https://github.com/Microsoft/TypeScript/issues/10178

Reproduce the report with main.ts and typings.d.ts using tsc main.ts, keeping the import from angular and the wildcard module declaration for *.html. Trace why the import in typings.d.ts prevents ./template.html from resolving. Done means the example compiles without TS2307 while retaining the import and wildcard declaration.