Fix bug when merging an array with a non-array

Author: colinodell

src/Util.php

@@ -47,7 +47,7 @@ public static function mergeAssocArray($to, $from, int $mode = DataInterface::RE
             return array_merge($to, $from);
         }
 
-        if (is_array($from)) {
+        if (is_array($from) && is_array($to)) {
             foreach ($from as $k => $v) {
                 if (!isset($to[$k])) {
                     $to[$k] = $v;

tests/UtilTest.php

@@ -126,13 +126,13 @@ public function mergeAssocArrayProvider()
             [
                 'Arrays should be merged/appended (when using MERGE)',
                 // to
-                ['a' => 1, 'b' => 1, 'n' => [1]],
+                ['a' => 1, 'b' => 1, 'n' => [1], 'x' => 'string', 'y' => ['stringindex' => 1]],
                 // from
-                ['a' => 2, 'c' => 2, 'n' => [2]],
+                ['a' => 2, 'c' => 2, 'n' => [2], 'x' => ['array'], 'y' => [2]],
                 // mode
                 DataInterface::MERGE,
                 // expected result
-                ['a' => 2, 'b' => 1, 'c' => 2, 'n' => [1, 2]]
+                ['a' => 2, 'b' => 1, 'c' => 2, 'n' => [1, 2], 'x' => ['array'], 'y' => ['stringindex' => 1, 0 => 2]]
             ],
         ];
     }