Merge pull request #130 from vidmantaskiro/get_phone-fix

get_phone return type fix

omnisend/includes/SDK/V1/class-contact.php

@@ -562,7 +562,7 @@ public function set_phone( $phone ): void {
 	 * @return string
 	 */
 	public function get_phone(): string {
-		return $this->phone;
+		return $this->phone ?: '';
 	}
 
 	/**