[Ref] Throw exceptions from Authorize.net rather than return errors

This is part of 'modelling good behaviour' - curently doPayment converts the errors to thrown exceptions,
but the recommendation is that the payment processor functions should throw exceptions themselves.
If they do they willl bypass the doPayment handling, but acheive the same thing

CRM/Core/Payment/AuthorizeNet.php

@@ -133,10 +133,7 @@ public function doDirectPayment(&$params) {
     }
 
     if (!empty($params['is_recur']) && !empty($params['contributionRecurID'])) {
-      $result = $this->doRecurPayment();
-      if (is_a($result, 'CRM_Core_Error')) {
-        return $result;
-      }
+      $this->doRecurPayment();
       return $params;
     }
 
@@ -237,36 +234,31 @@ public function doRecurPayment() {
 
     $intervalLength = $this->_getParam('frequency_interval');
     $intervalUnit = $this->_getParam('frequency_unit');
-    if ($intervalUnit == 'week') {
+    if ($intervalUnit === 'week') {
       $intervalLength *= 7;
       $intervalUnit = 'days';
     }
-    elseif ($intervalUnit == 'year') {
+    elseif ($intervalUnit === 'year') {
       $intervalLength *= 12;
       $intervalUnit = 'months';
     }
     elseif ($intervalUnit === 'day') {
       $intervalUnit = 'days';
-    }
-    elseif ($intervalUnit == 'month') {
-      $intervalUnit = 'months';
-    }
-
-    // interval cannot be less than 7 days or more than 1 year
-    if ($intervalUnit == 'days') {
+      // interval cannot be less than 7 days or more than 1 year
       if ($intervalLength < 7) {
-        return self::error(9001, 'Payment interval must be at least one week');
+        throw new PaymentProcessorException('Payment interval must be at least one week', 9001);
       }
-      elseif ($intervalLength > 365) {
-        return self::error(9001, 'Payment interval may not be longer than one year');
+      if ($intervalLength > 365) {
+        throw new PaymentProcessorException('Payment interval may not be longer than one year', 9001);
       }
     }
-    elseif ($intervalUnit == 'months') {
+    elseif ($intervalUnit === 'month') {
+      $intervalUnit = 'months';
       if ($intervalLength < 1) {
-        return self::error(9001, 'Payment interval must be at least one week');
+        throw new PaymentProcessorException('Payment interval must be at least one week', 9001);
       }
-      elseif ($intervalLength > 12) {
-        return self::error(9001, 'Payment interval may not be longer than one year');
+      if ($intervalLength > 12) {
+        throw new PaymentProcessorException('Payment interval may not be longer than one year', 9001);
       }
     }