Merge branch 'master' into processed_metrics_metadata

Conflicts:
	core/Twig.php

2 files changed, 15 insertions, 4 deletions

diff --git a/core/DataTable/Filter/GroupBy.php b/core/DataTable/Filter/GroupBy.php
index 9391ccd95f..2ac79a6de9 100755
--- a/core/DataTable/Filter/GroupBy.php
+++ b/core/DataTable/Filter/GroupBy.php
@@ -10,6 +10,7 @@ namespace Piwik\DataTable\Filter;
 
 use Piwik\DataTable;
 use Piwik\DataTable\BaseFilter;
+use Piwik\DataTable\Row;
 
 /**
  * DataTable filter that will group {@link DataTable} rows together based on the results
@@ -71,6 +72,7 @@ class GroupBy extends BaseFilter
      */
     public function filter($table)
     {
+        /** @var Row[] $groupByRows */
         $groupByRows = array();
         $nonGroupByRowIds = array();
 
diff --git a/core/DataTable/Row.php b/core/DataTable/Row.php
index a90855a1d9..c6c0d21e9f 100644
--- a/core/DataTable/Row.php
+++ b/core/DataTable/Row.php
@@ -640,10 +640,7 @@ class Row implements \ArrayAccess, \IteratorAggregate
             return $newValue;
         }
 
-        if (is_string($columnToSumValue)) {
-            throw new Exception("Trying to add two strings in DataTable\Row::sumRowArray: "
-                              . "'$thisColumnValue' + '$columnToSumValue'" . " for row " . $this->__toString());
-        }
+        $this->warnWhenSummingTwoStrings($thisColumnValue, $columnToSumValue);
 
         return 0;
     }
@@ -761,4 +758,16 @@ class Row implements \ArrayAccess, \IteratorAggregate
         }
     }
 
+    protected function warnWhenSummingTwoStrings($thisColumnValue, $columnToSumValue)
+    {
+        if (is_string($columnToSumValue)) {
+            Log::warning(
+                "Trying to add two strings in DataTable\Row::sumRowArray: %s + %s for row %s",
+                $thisColumnValue,
+                $columnToSumValue,
+                $this->__toString()
+            );
+        }
+    }
+
 }