Convert exception instanceof checks to assertions

Author: nikic

Zend/zend_exceptions.c

@@ -92,11 +92,10 @@ void zend_exception_set_previous(zend_object *exception, zend_object *add_previo
 		return;
 	}
 
+	ZEND_ASSERT(instanceof_function(add_previous->ce, zend_ce_throwable)
+		&& "Previous execption must implement Throwable");
+
 	ZVAL_OBJ(&pv, add_previous);
-	if (!instanceof_function(Z_OBJCE(pv), zend_ce_throwable)) {
-		zend_error_noreturn(E_CORE_ERROR, "Previous exception must implement Throwable");
-		return;
-	}
 	ZVAL_OBJ(&zv, exception);
 	ex = &zv;
 	do {
@@ -837,16 +836,14 @@ static zend_object *zend_throw_exception_zstr(zend_class_entry *exception_ce, ze
 {
 	zval ex, tmp;
 
-	if (exception_ce) {
-		if (!instanceof_function(exception_ce, zend_ce_throwable)) {
-			zend_error(E_NOTICE, "Exceptions must implement Throwable");
-			exception_ce = zend_ce_exception;
-		}
-	} else {
+	if (!exception_ce) {
 		exception_ce = zend_ce_exception;
 	}
-	object_init_ex(&ex, exception_ce);
 
+	ZEND_ASSERT(instanceof_function(exception_ce, zend_ce_throwable)
+		&& "Exceptions must implement Throwable");
+
+	object_init_ex(&ex, exception_ce);
 
 	if (message) {
 		ZVAL_STR(&tmp, message);