Fix sumif PHPOffice#683

Author: Sreten Ilić

src/PhpSpreadsheet/Calculation/Functions.php

@@ -267,7 +267,7 @@ public static function isCellValue($idx)
     public static function ifCondition($condition)
     {
         $condition = self::flattenSingleValue($condition);
-        if (!isset($condition[0])) {
+        if (!isset($condition[0]) && !is_numeric($condition)) {
             $condition = '=""';
         }
         if (!in_array($condition[0], ['>', '<', '='])) {

tests/data/Calculation/MathTrig/SUMIF.php

@@ -58,4 +58,28 @@
             [100],
         ],
     ],
+    [
+        100,
+        [
+            ['0'],
+            ['some text'],
+        ],
+        0, // Compare integer with string
+        [
+            [100],
+            [1],
+        ],
+    ],
+    [
+        100,
+        [
+            [0],
+            ['some text'],
+        ],
+        0, // Compare integer with integer
+        [
+            [100],
+            [1],
+        ],
+    ],
 ];