Refactor domain validation logic in ValidateDomainSniff

Do not allow current domain name to be empty. Notify the user with an error

Author: slaFFik

WPForms/Sniffs/PHP/ValidateDomainSniff.php

@@ -113,7 +113,19 @@ public function process( File $phpcsFile, $stackPtr ) {
 			return;
 		}
 
-		if ( ! $currentDomain || ! $expectedDomain ) {
+		if ( ! $currentDomain ) {
+			$phpcsFile->addError(
+				sprintf(
+					"Domain name is not set. You should be using '%s'.",
+					$expectedDomain
+				),
+				$stackPtr,
+				'InvalidDomain'
+			);
+			return;
+		}
+
+		if ( ! $expectedDomain ) {
 			return;
 		}