Fix/hack ErrorPageError to work from non-UI contexts

Right now, ErrorPageError *assumes* you're never running on the cli
or the API. It's kinda a crappy superclass to use for errors unless
you're 1000% sure you'll never hit that code path. Yay assumptions!

Ideally, all of this report() crap is cleaned up and unified across
the like 1192902117 places we have it spread out, but for now just
detect the scenario and delegate back to MWException, which does the
right thing

Bug: T168337
Change-Id: Ia2f490528e128527a7a5ef1f4f5eea36ec9ee810

includes/exception/ErrorPageError.php

@@ -61,9 +61,12 @@ class ErrorPageError extends MWException implements ILocalizedException {
 	}
 
 	public function report() {
-		global $wgOut;
-
-		$wgOut->showErrorPage( $this->title, $this->msg, $this->params );
-		$wgOut->output();
+		if ( self::isCommandLine() || defined( 'MW_API' ) ) {
+			parent::report();
+		} else {
+			global $wgOut;
+			$wgOut->showErrorPage( $this->title, $this->msg, $this->params );
+			$wgOut->output();
+		}
 	}
 }

tests/phpunit/includes/exception/ErrorPageErrorTest.php

@@ -43,6 +43,7 @@ class ErrorPageErrorTest extends MediaWikiTestCase {
 		$mock->expects( $this->once() )
 			->method( 'output' );
 		$this->setMwGlobals( 'wgOut', $mock );
+		$this->setMwGlobals( 'wgCommandLineMode', false );
 
 		$e = new ErrorPageError( $title, $mockMessage, $params );
 		$e->report();