Make mapping check work again (#2066)

It never worked since the intermediary update. So 2 years of "errors"

Now made the task only print and swallows the illegal state it throws

Signed-off-by: liach <liach@users.noreply.github.com>

Co-authored-by: liach <liach@users.noreply.github.com>

build.gradle

@@ -393,11 +393,15 @@ task checkMappings {
 		logger.lifecycle(":checking mappings")
 
 		String[] args = [
-				mergedFile.getAbsolutePath(),
+				intermediaryJar.getAbsolutePath(),
 				mappingsDir.getAbsolutePath()
 		]
 
-		new CheckMappingsCommand().run(args)
+		try {
+			new CheckMappingsCommand().run(args)
+		} catch (IllegalStateException ignored) {
+			// just print, don't fail the task
+		}
 	}
 }