fix out of bounds shift and pop behavior

src/Illuminate/Collections/Collection.php

@@ -797,9 +797,15 @@ public function pop($count = 1)
             return array_pop($this->items);
         }
 
+        if ($this->isEmpty()) {
+            return new static;
+        }
+
         $results = [];
 
-        foreach (range(1, $count) as $item) {
+        $collectionCount = $this->count();
+
+        foreach (range(1, min($count, $collectionCount)) as $item) {
             array_push($results, array_pop($this->items));
         }
 
@@ -963,7 +969,13 @@ public function shift($count = 1)
 
         $results = [];
 
-        foreach (range(1, $count) as $item) {
+        if ($this->isEmpty()) {
+            return new static;
+        }
+
+        $collectionCount = $this->count();
+
+        foreach (range(1, min($count, $collectionCount)) as $item) {
             array_push($results, array_shift($this->items));
         }
 

tests/Support/SupportCollectionTest.php

@@ -231,6 +231,8 @@ public function testPopReturnsAndRemovesLastXItemsInCollection()
 
         $this->assertEquals(new Collection(['baz', 'bar']), $c->pop(2));
         $this->assertSame('foo', $c->first());
+
+        $this->assertEquals(new Collection(['baz', 'bar', 'foo']), (new Collection(['foo', 'bar', 'baz']))->pop(6));
     }
 
     public function testShiftReturnsAndRemovesFirstItemInCollection()
@@ -249,6 +251,8 @@ public function testShiftReturnsAndRemovesFirstXItemsInCollection()
 
         $this->assertEquals(new Collection(['foo', 'bar']), $data->shift(2));
         $this->assertSame('baz', $data->first());
+
+        $this->assertEquals(new Collection(['foo', 'bar', 'baz']), (new Collection(['foo', 'bar', 'baz']))->shift(6));
     }
 
     /**